Right from the horses (Apples) mouth!
Sync .Mac Bookmarks with Safari before June 30, 2008
As part of the transition from .Mac to MobileMe, Web access to .Mac Bookmarks ends on June 30, 2008 (06-30-2008). After this date, you will no longer be able to access or update your bookmarks at (www.mac.com).
To avoid losing any existing .Mac Bookmarks, sync them with Safari on your Mac before June 30, 2008.
(Via apple )