My initial impression: “Yawn….”
You can download the software at http://talk.google.com. The one interesting angle I can see is the voice chat, but I don’t think that will get much exposure unless people really start using Google Talk as their primary IM client. The whole voice-chat thing always suffers from poor quality audio input/output on “typical users'” machines, so I’m wondering if that feature will really get any traction. Aside from that, the integration with Gmail is nice, but it doesn’t give me a whole lot more functionality than the Gmail notifier did.
One more IM on the market…
One Man Shouting 