I have a PS3 and prompted by your post, i hooked up an external hard drive i had laying around. It looked like it was going to recognize it, then it didn't. No extra options just for external drives either.
Some quick googling suggests that the PS3 requires the FAT32 file system and it cannot handel NTFS. Probably won't get around to trying this tonight, but i do want to play around with it as well.