Sometime last night, Firefox downloads crossed the 500 million threshold.
It's an arbitrary but interesting milestone for the open-source Web browser, whose development is overseen by Mozilla but that's also developed and extended by a large number of outside programmers. In September 2007, Firefox crossed the 400 million download mark, indicating an average rate a bit shy of 20 million per month at present.
According to the Spread Firefox site, there had been 500,168,448 downloads as of 6:15 a.m. PST. About 12 hours earlier, there had been more than 499,900,000.
Firefox has spread widely in the years since its release. The project originally was named Phoenix to symbolize a rising from the ashes of the Netscape open-source browser project that began in 1998 but languished for many years as Microsoft's Internet Explorer solidified its lead.
Now Firefox programmers are working on version 3, which brings performance improvements and interface changes, and Mozilla also is working on a mobile version of the browser for handheld devices.
A sister subsidiary of Mozilla, Mozilla Messaging, is working to reproduce the successes of Firefox with the open-source Thunderbird e-mail software.