It's up there now and according to the BBC its makers want it to be the most downloaded software in its first 24 hours ever. Firefox 3 is now available for public download, although the final release candidate has been so close to commercial standard you wouldn't be able to see much difference.
Personally I've adopted it as my browser of choice after using the final release candidate for about a week. It's solid, it's reliable anjd it does things I like - tabbed browsing is of course a given by now, but its memory of where you've been - offering you frequently-visited sites as you enter the address regardless of whether you've bookmarked them - is a plus.
Mostly, though, I like the speed. No doubt some more technically-minded individuals will be along any moment now to confirm exactly why it's so much faster than its predecessor or anything else I've used on the market (which in my case on the Mac takes in Camino, Safari, Internet Explorer and Flock) but it seems to me to just whiz along. When you're researching a story and on deadline as I often am, the absence of a wait does marvels for your blood pressure.
It does other stuff nicely. When I log onto my bank it gives me a bit of the address bar telling me who really owns the site rather than the headline name (this isn't anything similar, by the way - my bank is a subsidiary so I get the name of the 'main' bank as well). Searching for visited sites by keyword is also good. I could go on.
This is going to challenge everyone in the browser market. I wonder how long it will be before a manufacturer starts preloading it on their computers?