In delving into the XML file that Software Update uses to check for available updates, edibiase found that a MobileMe Updater is online. Forum member, FreeState installed it, and found that it changes all instances of ".Mac" to "MobileMe" and also provides a pretty new icon for the MobileMe service.
Apple is launching MobileMe tonight and we expect this updater to be officially available shortly. Adventurous users can install the file themselves (see thread). The updater also changes account references to @mac.com accounts to @me.com accounts in your Mail app, but still lists both @mac.com and @me.com addresses for use.