Google has released an audio/video chat plugin for their GMail service. I don't use GMail, so I'm not going to try this out personally, but from what I can tell, it is of the "browser plugin" type. To get it, you download and install a plugin, and you will then have a "Video & More" icon in GMail. They have apparently also made an agreement with Logitech and/or Buy.com to offer webcams at a significant discount for the next few weeks. There is a discussion in the GMail Blog, and the plugin can be downloaded here.
One thing that I find interesting about this is that it removes another possible candidate from the very small list of companies where eBay might be able to unload Skype. As I have said before, despite all the talk about whether or not eBay "wants" to sell Skype, their problem is going to be finding someone foolish enough to pay for it - and now this move from Google introduces significant new competition as well!