During an interview with MTV Multiplayer, Blizzard's Frank Pearce asserted that the feature is still on the way. "But it's not necessarily something we have a specific timeline for," he said, "which is unfortunate because one of the things that we've found is, especially from our learnings from World of WarCraft, is that these audiences that play these games are very, very passionate and want to experience lots and lots of content. With the StarCraft 2 client and the StarCraft 2 map editor and the Battle.net platform, it creates an opportunity for the community to serve itself with content, if the mechanisms are there."
To be fair, if it did have a timeline, it would be a Blizzard timeline, and therefore could only be specific to the year. Approximately.