"So much is happening on the Web right now, it's a great time for browsers," said John Lilly, CEO of Firefox backer Mozilla, in a statement. And, he boasted, "Firefox 3.5 brings together the most innovative Web technologies and delivers them in the most complete and powerful modern browser."
With the software released, Mozilla programmers and their open-source comrades now can move on to the next round of updates, to encouraging Web developers to build in support for the new features, and to finalizing new standards such as HTML 5.
Firefox broke Microsoft's lock on the browser market, but it now faces other challenges, chiefly Apple's Safari and Google's Chrome.
Mozilla released Firefox 3.5 in 70 different languages, taking advantage of the relatively broad internationalization that's more feasible with open-source software.
Through revenue that comes from search ads, Google supplied Mozilla with $66 million of its $75 million in 2007 revenue, the last year for which figures are publicly available.
Update 9:31 a.m. PDT: Mozilla has published a live download tracker site. It's showing the worldwide rate between about 80 and 100 downloads per second at present; I saw a peak of 109 per second.