TSA has just received confirmation from Sony about an strangely-timed period of server maintenance that will only affect games published by Sony Computer Entertainment Europe. The outage will take place tomorrow morning from half five until half past ten; including titles such as Killzone 3, Uncharted 2... practically anything published by SCEE. You'll still be able to log in to the PSN as normal - and all other games will remain unaffected.
Sony hasn't given a reason for the downtime as yet, so it's time for some rampant speculation. It's likely just a security overhaul... but many fans are wondering whether cross game chat could be in the pipeline for first-party titles. On the other hand, it could be something to do with the recently-revealed PSN Pass (hopefully it won't be a retroactive move to lock online content as I frankly can't see how it would be possible to implement). Either way, we'll know more tomorrow.