It's not just the remarkably lousy usability of Google's Gmail "integrated" chat, nor just Google's persistent notification chaos, it's everything to do with Google and communication services.
Check out the current state of one fragment of the Google Talk
Except when you click on the link for "Google Talk Gadget" you go to "Google Talk" (I think the Gadget might be gone) which is Windows only.
There is still a page for embedding a Google Talk gadget and you can add it via search to the iGoogle page, but in both cases the "call" button requires Google Talk for Windows.
Sheesh. This reminds me of Microsoft's web site chaos.
It's ugly out there.
PS. I looked at Mailplane as an alternative Gmail front end to see if that would provide notification services and improved usability for Google Video Chat. There is some support, but not enough to be worth the complexity of adding another app into the mix (two apps really, since it works with Growl.)