Have you upgraded to Mac OS X Lion, migrated from MobileMe to iCloud, and are now stuck with a Sync icon in your menu bar?  It doesn't seem to have any options for being removed.  Even Alt-Clicking the icon doesn't present a way to remove it.  You could Control drag it out, but I have read others found this deleted the sync settings from AddressBook.  Instead, go to System Preferences, enter MobileMe preference pane and sign out.  This will result in the icon being removed from the menu bar.