Sony has just released the next PlayStation 3 firmware update, which carries a version number of 3.66. This is a mandatory update for all consoles.
According to the PlayStation Blog, the purpose of this update is apparently to improve "system stability during use of PlayStation 3 format software and network services."
While very vague, hopefully this will make hard disks more stable when updating firmware and patches for various games - there have been numerous problems with previous updates.
Source: PlayStation Blog