So as of now blizzard has a pretty good layout of terran and protoss units and buildings but they are keeping us in suspense with the Zerg. I've seen a few fan art pictures of Ultralisks and such but nothing official. The only official thing I've seen from the Zerg was in their Demo preview.
but aside from that it looks like the zerglings have wings...
or are they spikes?
but nonetheless I cant wait to see the zerg units =]