I hope they improve the observer tools for SC2. Specifically, I'd like to be able to see an outline of each player's visible area on the minimap (most appropriately via a coloured line of the player's color at the edge of their visible area). That way I can better understand why the players are doing what they do, instead of watching from the observer POV, where you can see everything. That bit of information there gives you context for just how brilliant these players are.
I'd also like to see them allow user commentary and dubbing of playbacks, and even have it uploaded to battle.net
I've heard they're going to charge money for some things on battle.net... I wouldn't mind paying a few dollars for the ability to download good commentaries on good plays through battle.net
They should also include detailed stat breakdowns with graphs, giving your normal curves (or S curves) to help you see how you stack up against the population. Also have it filter for players with similar abilities/friendslists/etc.
For all the effort they put into make SC2 competitive game, those sorts of analysis tools will help as much.