Just a little alert if you have your Sametime Gateway working but federation to Google Talk does not work, or maybe it was working and then stopped. Tech note from support KB below.
We recently had this happen on a previously working IM connection to Google. Following the steps per the tech note did the trick by assuming administrative control of the domain within Google Apps.
After setting up the proof of domain control, it took a little under 48 hours for Google to allow us to change Google Apps settings.
After disabling Google chat within the domain, federation back to our ST Gateway was restored within about an hour.