According to one of the Japanese tech blog, iPad 3 may be out as early as March, 2012. Additionally, as per their ‘reliable Asian Source’, production of iPad 3 is being rushed simply due to Chinese New Year Celebrations which are from January 22nd to 28th. And also as per this site, iPad 3 will come with a redesigned dock...and i do believe IMO Siri will come along.
Cheer

Just do some web searching and u will get lots of update from there...