Overview:
History:
The world's first electricity generating wind turbine was a battery charging machine installed in July 1887 by Scottish academic James Blyth.

It was in 1951 that the first utility grid-connected wind turbine to operate in the United Kingdom was built by John Brown & Company in the Orkney Islands.

In 2006 Scotland put up the first 5 MW wind turbine.
In 2007 the European Union established a target of generating 20% of the EUÕs energy supply from renewable sources by 2020.
In 2008 the US DOE established a goal of 20% Wind Energy by 2030.
In 2010 the Scottish Government establishes a target of generating 31% of Scotland's electricity from renewable energy (most from wind) by 2011, and 100% by 2020.

In 2012, installed wind power capacity in the European Union totalled 105,000 megawatts (MW) - enough to supply 7% of the EU's electricity.

Wind power (2011-12):

            US  60   GW  3%
    South Dakota 8.4 GW 22%
            EU 105   GW  7%
United Kingdom  11.3 GW
Scotland         2.8 GW  21%
      Germany 29   GW  10%
          Spain        17%
        Denmark        20%
        Japan  2.3 GW  0.5%
        Canada 5.3 GW  2.3%

Capacity credit is the ability to replace other sources of power.
There are mismatches between supply and demand cycles. User demand is generally higher during the day, however wind varies from hour to hour, you can't easily save wind generated electricity (although there are some proposals of ways to do that which decrease efficiency and increase cost).
So you need backup power. Some forms like hydropower can be switched on and off the most readily. Some natural gas plants can also switch on and off quickly (though at a cost of efficiency, i.e., burning more fuel).
Capacity credits vary from 4% (German study) to 10% (New York State study) to 16% (U.K. estimate).
See: National Wind Watch | Output From Industrial Wind Power.

Source: Natl. Renewable Energy Laboratory - NREL.gov: Dynamic Maps - Wind Maps
Wind Energy Resource Atlas of the United States

New Jersey offshore Wind proposals:
According to a 2008 study by the U.S. Department of Energy (DOE) titled, "20% Wind Energy by 2030," it would require 300 GW. The Northeast has almost a third of the total capacity for offshore wind in the United States.

In 2007 New Jersey passed the Global Warming Response Act; The law mandates reductions in greenhouse gas (GHG) emissions to 1990 levels by 2020, approximately a 20 percent reduction below estimated 2020 business-as-usual emissions.

In 2008 the New Jersey Board of Public Utilities approved an initial 350 MW offshore wind farm, which will consist of 96 wind turbines 16 to 20 miles off the coast of Cape May and Atlantic counties. However, it has been held up by Governor Christie.

In 2010 New Jersey passed the "Offshore Wind Economic Development Act".
It was aimed to support the development of at least 1,100 MW of generation from offshore wind projects, with a goal of at least 3,000 MW of offshore wind capacity by 2020.
Through the legislation, the New Jersey Economic Development Agency (EDA) will provide financial assistance and tax credits to offshore wind project developers and manufacturers.
See: New Jersey Projects | Offshore WindHub

New Jersey is one of the best places for offshore wind because of the quality of wind (av. 15 - 20 MPH see above map) and a continental shelf that extends out 50 miles with depths around 65 ft. at 11 miles.
As of 2013 this plan has been held up by the Christie administration.
The towers would be 230 ft (70 m) tall. Power would be transmitted to shore thru underwater cables.

Specific advantages of offshore wind power include:

• Winds are much stronger offshore. Average annual wind speeds just a few miles offshore are typically 25 to 40 percent stronger relative to adjacent land areas. This speed advantage yields a 50 to 75 percent gain in energy production from a wind turbine. Offshore winds are stronger, more consistent and, unlike onshore breezes that pick up at night when power demand falls, tend to blow the hardest during the day.
  At a 65% gain a 2.5 MW turbine would produce about 9 million kWh a year the equivalent usage of 800 homes.
• The potential for large, contiguous development areas exist.
• Offshore winds are less turbulent. Lower turbulence means more efficient energy production. It also translates into less wear and tear on the turbines and components.
• Wind shear offshore is lower. This means that the boundary layer of slow moving air near the sea-surface is much thinner than what exists on land. This allows for the use of shorter towers offshore to reach a desired hub-height average wind speed.
• Visual impact can be reduced. Depending on siting location, the turbines can be installed distant from residents and land-based activities.

See:
New Jersey Offshore Wind Energy: Feasibility Study Nov., 2004
A Clean Northeast: Moving the Northeast Beyond Coal and Toward a Clean Energy Future, March 2011, Sierra Club
Offshore Wind A Step Closer, Jan 2013, New Jersey Chapter of the Sierra Club.
Plan for N.J.'s first offshore windfarm advances with test buoy anchored in federal waters | NJ.com, June 4, 2013
Wind power still tied up in N.J. politics | Daily Record | dailyrecord.com June, 2013
Wind power in New Jersey - Wikipedia

In May 2011, Cape May-based Fisherman's Energy submitted an application to the Board of Public Utilities (BPU) under the Offshore Wind Economic Development Act for a demonstration project to build six wind turbines 2.5 miles off the coast at Atlantic City, called Fisherman's Atlantic City Windfarm.
See: Atlantic City Windfarm | Fishermen's Energy - The Future of Energy in New Jersey

Transmission Backbone
In 2010 Google and Good Energies each agreed to invest heavily in a proposed $5 billion 350 mile transmission backbone for future offshore wind farms along the Atlantic Seaboard that could ultimately transform the region's electrical map.

The New Jersey segment of this offshore high-voltage DC backbone, known as the New Jersey Energy Link, could carry 3,000 megawatts of offshore wind power, allowing the industry to achieve economies of scale necessary for success.
See:
Wind Power Backbone Sought Off Atlantic Coast - NYTimes.com
Proposed wind farm off Atlantic City coast stirs debate over costs - Philly.com

New towers are constructed as a large tube instead of a lattice so there is no temptation for birds to land on them and the blades move slower.
See Bird Strikes and Electrocutions at Power Lines, Communication Towers, and Wind Turbines: State of the Art and State of the Science - Next Steps Toward Mitigation, 2005

Noise:
GE claims it is 40 dB(A) at 400 meters.
At Acceptable Noise - dBA at EngineeringToolbox.com they say 45 dBA is the upper limit for sleep with the window open.

Aesthetics:
One argument is they will spoil the view. (They said the same thing about a bridge across the golden gate in San Francisco).
If you are standing on a boardwalk 10 ft above sea level the horizon is 4.7 miles away, so only the tops of these towers will be visible beyond the horizon.

Cost:
The market price of offshore wind energy is about 50 percent higher than that of energy generated on land.

Glossary:

AWEA - American Wind Energy Association
BPU - Board of Public Utilities  
EWEA - European Wind Energy Association
GW - GigaWatts - one billion Watts (1,000 MW)
kWh - KillaWatt hours - One thousand watts, used over 1 hour (measure of home usage)
MARCO Mid-Atlantic Regional Council on the Ocean
NREL - National Renewable Energy Laboratory
MW - MegaWatts - one million Watts
OCS - Outer Continental Shelf
RFC - Reliability First Corporation 
PJM - A regional transmission organization (RTO) that coordinates the movement of
wholesale electricity in all or parts of 13 Mid-Atlantic states.