Google is aware of the problem that is causing Google Talk to be down for most people, including me. The problem appeared early this morning, and Google updated the downtime status twice on the Apps dashboard over the past hour and change.
We’re aware of a problem with Google Talk affecting a majority of users. The affected users are able to access Google Talk, but are seeing error messages and/or other unexpected behavior. We will provide an update by 7/26/12 7:50 AM detailing when we expect to resolve the problem. Please note that this resolution time is an estimate and may change.
We will update, hopefully soon, when things improve.
Update: 9:15 ET. We are able to see our contact list and some IMs are going thru. However still not back to normal.
Update: 10:50ET Google updates that service to some users has been restored but not all (including me).
Update: Noon Google says it is back up:
7/26/12 11:25 AM
The problem with Google Talk should be resolved. We apologize for the inconvenience and thank you for your patience and continued support. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better. If you are still experiencing an issue, please contact us via the Google Help Center.