To transfer files TO a ps3 you need compatible files to transfer... eg a game save.
data cannot by copied OFF the ps3 with a thumbdrive anymore due to all the gamesave trophy hacks that happen so sony has disabled copying game saves. you cant save game data utility either.
The only way to get stuff on and off the ps3 is to jailbreak it then use ps3ftp or black box to copy and paste files.
p.s it will come under hack or exploit as this is the only way now.