This is Firefox 3 live day. They have been promoting Download day for a while. At this time though it looks like the mozilla’s website has gone under due to the traffic volume. I can not get the site to load. I will try later. Download here.
Update: I got the site to load but the download link is still for Firefox 2.
Update 2: Try this direct download link for the Windows version of firefox 3. Bwana McCall posted links over on FriendFeed for Linux and MAC as well.