7.1 million is the official 24-hour number from Mozilla: previous statistics you may have seen posted elsewhere on the Internet were simply estimates made by third-parties. Most of these were based on what was seen on the Firefox 4 Download Stats page, which now shows a counter over 17 million.
It's also worth noting that this number is just over three times what Microsoft achieved in the first 24 hours of the IE9 release: 2.35 million downloads. It's certainly impressive and shows the loyal following that Mozilla still has. Microsoft may have the advantage of being able to push new versions of IE through the Automatic Updates function of Windows Update, but it hasn't leveraged that yet.
While the Firefox 4 number is worth writing home about, it's certainly not what Mozilla was hoping for. The current record holder is still Mozilla, but with the previous version of its browser: Firefox 3 saw over 8 million downloads in a 24-hour period on June 18, 2008.
Despite the growing number of Firefox users (remember, even if Firefox is losing market share, the number of users on the Web continues to grow), Mozilla was not able to beat its own record. While the number is definitely worth celebrating, the organization should still be a little bit worried as it continues to lose loyal users to Google Chrome.
"As we do so much more online, we must expect so much more from our browser environment," a Mozilla spokesperson said in a statement. "We should expect it to know who we are, wherever we go. We should expect it to remember such simple things as history, passwords, open tabs, open applications – and remember those on our behalf, wherever we go online, on any device, and without the need to re-enter anything. We should expect it to move at human speed, while being completely customizable and yet so simple and intuitive, anyone can use it. We should expect it to enable us to live in the level of privacy and security WE choose to, everywhere WE go. In short, we should expect our browser to answer to no one but us!"