Google Wave has been long expected. In the meantime, Skype does pretty much everything this much vaunted technology espouses to do, and much better.
If Wave enabled you to aggreagte your Yahoo, Skype, MSN and other IMish services it might have a chance.
As it stands, it is a very marginal and curious technology.
Google's predilection to release technology to a closed base works against them; Gmail may be popular, but it was so difficult to get onto that I still use Yahoo! mail. Wave is now available to lots of people with no one to 'wave' to, so, who cares?
Google may have a narrow business model which generates a lot of money for them, but the company is otherwise clearly full of absolute idiots. YouTube proves this, as does practically everything else the company has done. Google only succeeds when it becomes truly evil and dominant, e.g. GPS, or books.
I really, really wanted Google Wave to work. All it turns out to be is an embarrassing wannabe IM with no one to talk to...