The IE9 Beta installer is now officially available for public download and can be grabbed from the direct download links provided below, the web-installer stub is just 2.37 MB in size which downloads the remaining setup files (roughly 24 mb on Windows 7 32bit) and surprisingly requires a system reboot to install (the only web-browser to do that).

First public beta of Windows Internet Explorer 9 is going to be released in 7 days from now on September, 15, but it seems the IE9 Beta Installer is now leaked outside Microsoft as a website claimed to have the setup also posting the video below demoing the release.