For those who wanted to wait for the official announcement from Mozilla, they have now added it to their download site
As promised, Mozilla has released version 4.0 of its popular browser (on time) to its official download page after two Release Candidates found their way to testers earlier this month; And Mozilla will be hoping to top their previous Guinness World Record
of 8,002,530 downloads within 24 hours for Firefox 3.0, which took place in June 2008 with parties in over 25 countries.
At the time of posting Firefox 4 had been downloaded 384,614 times according to the Mozilla download page, you can also view a map of those downloads (updated real time, hourly) here
, which appears to show a different number.