If you've been contemplating the $99/year renewal of your MobileMe account, you should probably hold off for a little while longer. Unless you're totally reliant on MobileMe and your account is about to expire, wait until after WWDC next week.
Apple is planning on doing something big with its cloud services, and MobileMe will most definitely be a piece of the puzzle. The MobileMe features that you use now (email services, calendar sync, etc.) will most likely be free services from Apple very soon...