Here's some info on the Zerg:http://news.filefront.com/whats-new-wit ... rcraft-ii/
One thing I'm sorta wondering is how they're going to explain the evolution of the Terrans / Zerg / Protoss in the context of the StarCraft storyline.
One possibility that occurs to me is that maybe each of the Terrans / Zerg / Protoss were conducting research on a "next-gen" army in secret since their wars weren't going as well for them as they had hoped. StarCraft I was with the original forces and StarCraft II was with the new ones.
ie. the Protoss in SC2 should be seen not as being changed from those in SC1 but rather as being upgraded.
It'd be cool, also, if you could play SC2 armies against SC1 armies. eg. SC2 protoss against SC1 zerg. The SC2 protoss, by virtue of being upgrades, could totally dominate over the SC1 zerg, even though the SC2 protoss would still be evenly matched against the SC2 zerg (for example).