Yes they are estimated march 2012, here is whats expected to be on it :
Retina Display: Strong rumors suggest that the iPad 3 would be armed with retina display, offering 2048×1536 pixels resolution.
SD Card Slot: Expectations of people are that Apple might introduce an SD Card slot in iPad3.
Improved HDMI: Though iPad 2 supports HDMI playback, one needs an additional digital AV adapter costing $39 more. Hence, expectations form iPad 3 is that it should have an HDMI port eliminating additional HDMI cable requirement.
Camera Flash: People expect an iPad 3 to have a camera with flash.
Thunderbolt: A Thunderbolt port is expected in the iPad 3, thus offering power and data connecivity at faster speed, using same connector.
Wireless Synchronize: Unlike wired connectivity, iPad 3 is expected to offer wireless synchronization of content.