You really need to Instant Message, but wanted to wait until Google entered the fray? Today's the day for you. Need a pal on Google talk to test with? I'm ThinkHammer.
UPDATE: What an amazingly lean interface and application! It downloaded and installed in seconds. I've given it a very small test and it looks great so far. Without default encryption, dialing in and out, and the other features of Skype, or the established user community of Yahoo it's hard to see how Google wins the instant messaging battle in the short term, but with their money and talent they can play the long game. We'll see.