Firefox 5 is not yet released. I browsed their FTP (ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/5.0/) and opened the index.html file and saw this: "We aren't quite finished qualifying Firefox 5 yet. You should check out the latest Beta. "

It's obvious that the guys at technobolt.com noticed the availability of some builds in the FTP and thought that they are the final 5.0 builds.