Hmmm. I'd guess we're going to see the Xel'Naga as a side in this, could that be what some of those odd units on the screenshot page are? What about the Zerg/Protoss hybrid they hinted at? Surely they can't balance 5 sides as well as they did the original 3, which they got pretty lucky with in the first place.
Those graphics do look nice though. Not too over-complex, and it looks to handle a ton of units on screen. Here's hoping it runs nice and responsive.
EDIT: Or not. Looks like the units I couldn't identify are some kind of Protoss mini-Dragoon.