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The worst kept secret.
I'm running Google Talk, Google's new IM client. Currently it doesn't seem to work with anything but other Gmail users, so I can't do a lot with it.
It might have been a bit more effective initially if it supported users of other services.
Hey, it supports voice as well, but who can I really call at this time of the night. I see that they've carefully noted that they are not a telephony service:
Google Talk is not a telephony service and cannot be used for emergency dialing.