|There's some freaky looking beastmen...|
Faeit 212 recently posted up some rumors doubtless gleaned from one of the big forums, but he didn't specify which one. Poke around places like Warseer and Dakka and you'll probably find more commentary.
Some of the interesting bits were more confirmation that full-on Chaos Marines are eventually going to be differentiated from Renegades, which should make a number of people happy, and will let GW sell more Land Raider variants and Land Speeders to Chaos (Renegade) players. Also, there are hints that Lost and the Damned and traitor guard focused armies may well be a part of this cycle.
Aside from rules updates, one would expect some new model releases, both resculpts and perhaps some new kits as well as some conversion sprues. So put aside some of that Necron money and start saving now!