It was released this morning at 10am PDT but you can't get to it
from their page. Here are direct download links:
MacOS (en-US): http://download.mozilla.org/?product=firefox-3.0&os=osx&lang=en-US
Linux (en-US): http://download.mozilla.org/?product=firefox-3.0&os=linux&lang=en-US
Windows (en-US): http://download.mozilla.org/?product=firefox-3.0&os=win&lang=en-US
Linux (en-US): http://download.mozilla.org/?product=firefox-3.0&os=linux&lang=en-US
Windows (en-US): http://download.mozilla.org/?product=firefox-3.0&os=win&lang=en-US