I have been using Lightroom 4 for the last few weeks. Getting ready to demo some of the awesome features at the Old Car City workshop next week. Apparently Amazon accidentally put up a pre order page for Lightroom 4 with a release date of March 6th.
Also Apple has been sending out invites to an iPad release announcement on March 7th. It maybe the iPad 3 or just an upgraded iPad 2s (like the iPhone). I'll be standing by, that's for sure.