If you rely on Google Talk for your chat services, we have some bad news for you — Google has confirmed that Talk is has been down for at least a few hours, with no clear timeline on when it might be back up. At 6:40AM this morning, the status for Google Talk was changed to "service disruption," and an hour later that was changed to a full service outage. Google said then that the "majority of users" were experiencing problems with the service, in the form of error messages and other "unexpected behavior" even though it appears you can log in to the service. Google's latest update was at 7:50AM, when the company said that they expected to provide an update any minute now with details on when the service will be back. Of course, Google said an hour earlier that it already would have given us those details, so there's no telling when exactly the service might be up.
Update: Google's 8:50AM update brought no news — the company says that at 9:50AM it'll provide more information on the issue, essentially the same message we've seen for the last few hours. Notably, Google's no longer saying that it'll have an update on when the issue will be resolved, though. So far, there's no end in sight.
Update 2: Another hour has come and gone, and the message stays the same — Google is investigating, and will have an update for us soon. That said, some users on Twitter are reporting that Google Talk is functioning again, so it seems the problems may be lessening in severity, at least.
Update 3: Google's making some progress. We're finding that Google Talk is working normally, and Google just updated the service's status to say "service has already been restored for some users, and we expect a resolution for all users in the near future." The issue has been downgraded back to "service disruption." Hopefully, the worst is over.
Update 4: According to Google's status page, Google Talk service has been fully restored.