Cools! was here...
Another way that the new content system improves the bandwidth picture is by requiring each user to download less data. With the Steam content system that’s been in place for a few years now, if an individual file on disk were modified by a game update, your client had to download the whole file. That can be painful when the file in question is really large. The new system supports delivering only the differences between the old and new files, meaning game updates will be much smaller overall.
In addition, the new content system will allow us to build several new features that we’ve often heard requested. Upcoming client releases will include things like download scheduling, bandwidth throttling, and prioritizing which games get downloaded first. You’ll also be able to download an update to a game while you’re playing that game; Steam will apply the update after you exit the game.
Wow, you may finally be able to use Steam now Idol.