Firefox has come a long way since it spawned from Mozilla five years ago, and has achieved many milestones worthy of celebration. Another one is on the way; with Mozilla announcing that they are nearing a total of one billion downloads. They are excited enough about the prospect of this happening soon that they have announced the opening of a site next week that will cover Firefox's history and its immense growth.
Mozilla is estimating about 20 downloads per second worldwide, with a little under 1 million to go before they reach that 1 billion mark. At that rate they'll have reached it before or during this weekend. While this in no way reflects the actual number of Firefox users worldwide, it does indicate the high level of demand people have for the “alternative” browser.
It was only about a year and a half ago that Firefox had managed reach 500 million downloads, indicating that in more recent times demand for the browser has increased tremendously.