Sony has released firmware version 2.43 for the PS3. According to the US Playstation Blog, it is mandatory to install it in Japan but optional everywhere else, provided you're already on 2.41+. The Sony PS3 UK website details that the update is to enable support for the the release of rental content on the Playstation Store. Not sure if do anything for other region machine though.
For those who want to get it, just go to Settings>Network Update and the 2.43 update will show. Alternatively, the download page can be obtained from Sony's website.