In an attempt to clear out the clutter, Google has disabled a handful of old services that have been replaced by newer options or simply aren't needed anymore. This includes Google Sync, Google Calendar Sync, the Issue Tracker API and SMS event scheduling.
This may sound awful, as sync is an important part of Google's services and something they do well, but calendars already sync (and still will sync) with CalDAV just like contacts will with CardDAV and so on. These open-source technologies will now take precedence over previously used proprietary ones like Microsoft Exchange. (For those of you using iOS, just follow these instructions if you want to make sure your iDevice is working with the newer sync options.) For more details, hit up the Official Google Blog.
Winter Cleaning [Official Google Blog]