Blizzard updated the official StarCraft II site today with a preview of how the revamped Battle.net will function. They emphasize the social features, competitive matchmaking system, and the ease of sharing mods and maps. Quoting:
"When the legacy Battle.net service introduced support for user-created mods such as DotA, Tower Defense, and many others, these user-created game types became immensely popular. But while Battle.net supported mods at a basic level, integration with tools and the mod community wasn't where it needed to be for a game releasing in 2010. The new Battle.net service will see some major improvements in this area. StarCraft II will include a full-featured content-creation toolkit — the same tools used by the StarCraft II design team to create the single-player campaign. To fully harness the community's mapmaking prowess, Battle.net will introduce a feature called Map Publishing. Map Publishing will let users upload their maps to the service and share them with the rest of the community immediately on the service. This also ties in with the goal of making Battle.net an always-connected experience — you can publish, browse, and download maps directly via the Battle.net client. Finding games based on specific mods will also be much easier with our all-new custom game system, placing the full breadth of the modding community's efforts at your fingertips."