Following the release of PS3 firmware version 2.0 earlier this month, Sony has rushed out a minor update that will fix a handful of bugs that arose in last firmware update including a glitch in the new Remote Start feature that caused the PS3 to unintentionally turn on.
The 2.01 firmware update fixes this issue as well as a few stability problems with the new Information Board, Internet Browser and the upscaler for PlayStation 2 games. One of the issues that came to light with firmware 2.0 relates to a host of technical issues with Assassin's Creed including frame rate issues, screen tearing, and game-stopping. Apparently, the patch fixes these issues but some users are now reporting problems with Call of Duty 4, so if you own the game it may be wise to wait a few days.
As usual, the new firmware is available for download using the PS3's network update feature or directly from Sony's Network Update page.