I was going to register in a more appropriate forum, but since there's SC fans here too, I thought what the heck.
So would you like to see a new race in Starcraft 2? I would, although it's hard to come up with a race differing greatly from the others while attaining the superb balance the original game is known for.
I've come up with a 'race' that is essentially comprised of Von Neumann nanobots. The Terran would have had problems fighting the Zerg until they finally came up with a way of creating a self-replicating nanobot (Von Neumann machine) and the ability to control them. They would beat the Zergs easily with the vigorously spawning machines that gather integration/disintegration information from signals sent by the Terran commanders.
The problem would have been in that the scientists created a very progressive evolutionary algorithm to enhance the nanobots' co-operativness. That would lead to an emergent behavior of the nanobots, which results in group intelligence. Just when the Terran are about to disintegrate their useless army, the self-aware assemblance of nanobots would attack them fiercely as a defence. Because the nanobots know the weaknesses and strategies of their builders, the Terran would have to plead assistance from Protoss.
So basically the nanobots would be unique in the way that every unit is built of number of nanobots and all except the self-aware units could be disintegrated to a collection of nanobots. For example, you could start disintegrating buildings (made of nanobots) and end up with X number of nanobots that can be ordered to integrate to form whatever can be formed with X number of nanobots, like fighting units.
The Blizzard team seems to have eliminated some of the things I hated in the game like the colliding and stucking units. They have retained the hilarious ledges and ramps though. What annoyances would you like to see changed in Starcraft?