Just released is the final alpha of the Firefox 2 web browser. Here's what's new since the alpha 2 release.
Update Jun 1st: So I've been using alpha 2 and then alpha 3 for some time now, and both were stable releases. Really I can recommend you use alpha 3 over Firefox 18.104.22.168. Not as many extensions are supported, but it's just as stable and you're missing out on some cute features.
The next release, beta 1, is due on July 6th. Hopefully that release will feature tab overflow as lots of times I have many tabs open and this is noticeably missing.