About an hour ago (10:00 AM PDT/17:00 UTC), after more than 18 months since the first Alpha (December 8th, 2006) was released and nearly 3-years in development Firefox 3 has been released. However, chances are you won’t be able to get it without a bit of wait. Mozilla wanted to get it the Guinness Book of Records for the most downloads within a 24-hour period. As a result all of Mozilla’s servers are overloaded.
Earlier it was taking several attempts just to connect to getfirefox.com, however now users are getting a Http/1.1 Service Unavailable error when attempting to connect. When I was able to connect it was still offering for me to download Firefox 126.96.36.199 instead of Firefox 3. spreadfirefox.com is also overloaded and don’t even bother with the Mozilla FTP sever as you will get ‘too many connections’ error.
The best thing to do is try back in a few hours when traffic may die down and Mozilla has a chance to up their servers’ capacities. You can also try the FTP mirror site such as that of Oregon State University’s Open Source Labs. That server (for now) appears to be working but that could soon change as well. Also I am not sure if downloading for this source would count towards the Firefox 3 Download Day 2008 pledge.
One more thing, with the release of Firefox 3 today, the clock starts ticking now for the end of Firefox 2 support and updates. Expect the last update to on or around December 17th. However as mentioned prior, about that time Firefox 3.1 will be released.
Edit: a reminder you can NOT get Firefox 3 via the ‘Check For Updates’ function in Firefox 2. Your best option is to keep trying at getfirefox.com