A new version of the multiplayer browser Battle.Net will debut with Starcraft II. How will it be superior to the previous version? Well, it'll be able to hit you up for money.
During a BlizzCon '08 panel discussion, Diablo 3 director Jay Wilson said, "We are looking to monetize Battle.Net so that we get to keep making these games and updating features. We kind of have to." Blizzard wants to avoid putting in a subscription but yes, some as-yet-unknown features will cost money.
Apparently Activision really likes the word "monetize". They've been using it a lot lately, first with Guitar Hero: World Tour, then with Call of Duty: World At War, and now Battle.Net. Guess they've settled on a strategy for their top franchises from here on out.
Quite possible the paid content for Battle.Net is something superfluous, like custom avatars for the browser. If they tried to sell special items or some such, an angry mob with pitchforks would gather. It's also possible Wilson was talking about additional episodes for the game. Whatever it is, be sure to keep your wallet handy. More PlayStation 3 News...