According to a report from Macotakara, which cited "a reliable Asian source", the next generation iPad is being rushed into production thanks to Chinese New Year celebrations lasting from January 22nd through the 28th. Factories in China are all gearing up to produce the iPad 3 by the end of January 2012.
Assuming that the source is reliable (An unreliable source on the internet? I don't believe it...), the new iPad is said to include a redesigned dock connector that features the same number of pins but in a smaller shape than the one the current iPad uses. If this is true, the new connector could pose a serious problem with existing products that plug into the dock.
In addition to the new connector, the tablet's screen will also remain the same size, even though the source didn't mention if Apple would increase it to Retina Display levels or continue on with the current resolution.
This report isn't the first, however, it joins a small number of previous iPad 3 rumors that have already surfaced. Different sites and sources have been in constant debate as to whether or not the new iPad would offer a 2,048 x 1,536 display. A move like that would give the tablet the same resolution as the current iPhone 4 and 4S as well as the iPod Touch 4G.
As far as a launch windows goes, you are probably looking at a March 2012 release date, especially considering the fact that Apple unveiled the original iPad in April of 2010 and the iPad 2 in March of 2011. Nevertheless, the Linley Group, a chip consulting firm, believes that Apple will outfit the iPad 3 with an A6 processor. This could also potentially push the launch back until June 2012 or later.
Source: CNET - iPad 3 could launch in March, with connector issues, report says