According to the Official PlayStation blog, PS3 firmware 2.43 has just been made available on Sony servers, but only constitutes a mandatory download for users in Japan.
No details were given on any bug fixes or functionality upgrades, so we can safely assume this is non-essential for other territories. However, should you feel the need and absolutely have to update your console to the latest version, 2.43 is available as a manual install from the XMB interface in all territories.
Judging from the comments thread and other sources, no issues have been reported on install, so fire away if you absolutely have to. You’d be better off saving your time and playing the likes of Ratchet though.