This might have effected you last night, especially if you were running Linux on your XBox 360 in order to process SETI@Home faster. Otherwise, you’re just fine.
The patch closes a hole that allows for an unsigned code injection, allowing users to potentially run Linux or other homebrew code on their expensive gaming consoles. Seriously, guys. It’s an XBox 360. Hack your regular XBox, play some games for a few years, THEN install Linux. Enjoy what you have for a little while before tearing it to bits.
Microsoft patches Xbox 360 [News.com.com.com]