According to developer Mathieulh, the official PS3 firmware v3.56 is said to contain a rootkit which allow Sony to perform remote code execution upon connection to the PlayStation network. What this means is that Sony can scan for specific files on your PS3 console—such as custom firmwares and hombrew applications—and send a report back to the company. Whether this is legal or not is yet to be determined but be careful what you put on your PS3.
Sony has secretly released a new version of the 3.56 firmware, version 2, which fixes a major bug in the previous release. The bug, which is now fixed, involved user upgraded hard drives showing up as corrupted. Sony silently pushed out the new 3.56 PUP, attempting to cover up the fact that they dropped the ball on the original 3.56 release. It appears to be a common trend with Sony, that quality assurance goes out the window, anytime a new firmware update is urgently pushed out for release by them.-http://psgroove.com/content.php?726-Sony-Silently-Releases-3.56v2-Upgraded-Hard-Drive-Bug-Fixed
