There have been a lot of pushing back and forth on what is going on for this year, and I think we are finally starting to get it down and get some sense of order for release dates. Or maybe the coffee really isn't kicking this morning. Either way, here is my own sense of what is going on from the various sources alongside some misc rumors about future releases.
There has been some comments asking what the current thinking is on the release dates, and it boils down to these currently.
2012
June: Flyer Releases. (3 Ork flyers), Stormtalon, Necron Doomscythe and NightscytheJuly: 6th edition hits the streets early
August: 40k wave (flyer possibilities) Also a chance for Chaos Marines codex
September: Starter Set with Chaos and Dark Angels
October: Chaos Space Marines (unless already released in August)
November: 40k Models (chaos)
December: Hobbit
2013
Tau
Dark Angels
Eldar
via Harry I am pretty sure Tau are the first release of 2013 and I don't think the Eldar are far behind them.