As this is something you guys seem to be pushing for the community, and an idea that I really like, streaming needs some help. Notably, it's not interesting for the viewer if they can't clearly see the results of rolls, and it's not really feasible to train your players to read out the numbers all the time, as that slows down the game.
The Group Play option of MasterPlan has a neat little function in that it has the ability to display rolls in a large, easy-to-read black window; such as 1d20+12 vs AC. Then shows, say "22! Hit!" and then the damage roll as well. Naturally, you should be able to spice this up; perhaps player text colour, with the Player/Token name and image in a corner to make it easily identifiable who's rolling, what they rolled, and if it was a hit, miss, or crit.
This is important to keep the viewer engaged in combat, especially in less engaging combat games, such as D&D 4e, where the tactics and planning are more important than what happens, and it's so regimented that off-the-cuff, and wild ideas aren't as commonplace as in other games.
Naturally, the functionality would be important to diversify to support other games, such as Exalted (showing the total hits and doubles), or Shadowrun (The number of hits and the number of exploded dice, followed by the total). It's a minor function for most players, but has a use for easy-tracking for the group as well, and not only for streamers.
Overall though, I find the support for streaming and Roll20 to be an excellent alternative to Maptools for a 'lighter' system and a solution for people with hosting problems there, and it has a lot of features I'd love to make use of in a game at some point. You have me intrigued, and I hope that you look to support the streaming aspect as much as the gameplay aspect :)