Sony has begun rolling out a new, mandatory PS3 system software update (version 4.66).
While the U.S. branch of PlayStation have yet to update their support page, the UK has already detailed the main feature of the update. Like most of these unannounced updates, it merely improves system software stability during the use of some features. Vague, as usual.
@UltimatePS3fr System software stability during use of some features has been improved.
— Chris Owen (@Envisager_) November 19, 2014
Sony notes that you'll need a minimum 200MB of free space in order to download the update, although the actual update is only about 44MB in size.