It seems that this update was issued to fix a vulnerability already known to the Free60 Project. This vulnerability has been successfully exploited to run arbitrary code, and a complete end user compatible hack has been in development for some time and is planned to be released on free60.org shortly. It will allow users to take back control of their Xboxes and run arbitrary code like homebrew applications or Linux right after turning on the console and without the need of a modchip, finally opening up the Xbox 360 to a level of hacking as the original Xbox.