I don’t trust Wikipedia, but I guess I will throw this out there for those that like rumours. According to the wikipedia article on the next (7th) expansion pack, it is going to be known as “The Sims 2: Free Time”. Personally, I like that better than “The Sims 2 Hobbies”. We should know pretty soon on what it will be called officially.
Also, the release date on that page says February 12th, 2008. I wouldn’t say that is the exact date, but it is safe to safe it’ll be out in the February – April timeframe.