I run Fx 3.0.8 everywhere (including a large corporation which standardizes both Macs and PCs on Fx) and I haven't had personally -- or even heard report of -- a single crash.
I don't want to say that it doesn't happen, but is it possible there are other circumstances causing this behavior?
It's very likely. Right now that's the big argument on the Mozilla support boards. A group is complaining about the consistent crashing and the others are are going about it like Firefox 3.0.8 is absolutely flawless and the mere hint of a possible crash is a ridiculous and unfounded assumption.
People with the issue are submitting logs and crash reports but no one has spotted anything yet. It's baffling. So far the only common ground is that the problem seems to be isolated to Windows XP and Vista systems only, I haven't come across any reports of the problem occurring on Mac or Linux. I have seen it happen on Windows XP running on a Mac though
I'm holding off on Opera mainly because it doesn't have Xmarks (yet) and it'd be a bitch to redo all my bookmarks again. I'd transfer them with another method if I could, but the truth is my heart still belongs to Firefox.