It's not up on Blizzards site yet but it's on youtube (Man, everything's on youtube these days )
It's a Zerg vs Protoss on a new map with the space tileset with the Zerg at 12 and Protoss at 2.
They show off the Protoss Nullifier with its forcefield ability which is used to great effect. It also got antigravity which is taken for a spin.
The Zerg Infestor got mindcontrol which is insanely powerful and is used for maximum power.
To summarise, it's a lot of back and forth battles with some gamechanging moments (ninja moves also called) that change the tide of the game quite a few times.