You cannot, they are system files for a reason, your system needs them, remove even one and it could prevent the ps3 from working properly, worst case brick it.
It also sets aside space for other things which you may decide to install, but still no way to make that space available for other things.
Either way you will not "see" where it has gone because it's reserved by the PS3. The space is empty until the PS3 requires to use it, eg. whilst playing a game or something.
There is nothing you can do to gain that space back, only thing you can do is install a larger hdd. But note that even then you will lose space. Quick search shows that installing a 1tb hdd, almost 100gb is reserved by the ps3!!!
This is just how the ps3 devs have developed the ps3 system, obviously on a 1tb the ps3 will never need that 100gb of space, but since the ps3 reserves space via percentage of hdd, the larger the hdd, the larger the reserved hdd space.
Also isnt uncharted 3 a little larger than 30gb? I heard it was 45gb-ish
Have you installed any themes or use Home or any of those other PSN features? All of those would copy files to the hdd.
Also, if you have been using the system for a while, you build up a lot of garbage. If you have CFW you can manually delete this stuff...otherwise you need to go to the recovery menu and select, "restore PS3 system" to wipe the drive completely (the "full format" option from the XMB is mislabeled; it does not do a format at all and won't delete the junk files)
30 gb sounds like too much for system files. I would guess its game installs. I dont know exactly, but under game, scroll all the way up, and look through there (not game saves). I cleaned out my installed old games and saved about 15~20 gb.
