Originally posted by Kroothawk on Dakka²:

The new mid size stompa thing looks like a pregnant Deff Dread. Comes with various weapon mountings, including what looks like a KFF.
New Gretchin models, including a grot oiler.
New mega nobs, not plastic versions of the existing.
Big Mek in mega armour with some interesting KFF like add ons.
Big Mek in Mega Armour with shoulder mounted weapons, maybe SAG but doesn't look like it.
Warboss is similar to the remodelling of the Helbrute from Dark Vengeance, it looks like a reworking of the AOBR Warboss with an attack Squig
New Pain Boy with a kind of Narthecium cybork hand.
Flash Gitz (They look particularly awesome, very much like Freebootaz with loads of variation in the kit).
Big Gunz. Total redesign.
This fits with some things I have been told. The application of salt is advisable though. Since 40K 7th edition can't take up too much space in the release order, I guess some of this might drop sooner rather than later. Mid/late June possibly.