Windows only: Give the new Firefox 3.1 beta a test drive without compromising your stable 3.0 installation with the portable version. The speedy folks at PortableApps.com are now offering Firefox 3.1 Beta 1 as a standalone application you can run from a self-contained folder on your desktop or your USB drive. Check out what's new in Firefox 3.1 here; the portable version is a free download for Windows only.