Check out this amazing website from Mozilla. This website displays Firefox 4 live download stats dynamically. Since its official launch a few hours back, there have been 1,440,231 downloads and counting!
When someone clicks the download button on mozilla.com or asks for an upgrade from inside Firefox, we approximate their location based on IP address and store anonymous aggregate location information in our database, says Mozilla.
You can see the downloads continent wise as well as country wise.
You definitely want to check out glow.mozilla.org !