For PS3 gamesaves: There are two types, those which are encrypted and signed, and those which aren't. This allows modifications/cheats for some games, yes. When copied, they are put inside these folder called "PS3\SAVEDATA\", followed by their Title ID.
This ID is unique for each title running on the PS3. It has the following syntax (where A is any upper-case alphabetic character, and 0 is any decimal number): AA0000-AAAA00000_00-AAAA000000000000
Often a new character is added to the back in file-names containing ID's, which is probably used to determine the title region (PAL/NTSC).
Photo Gallery IP9100-NPIA00006_00-VSHMODULE0000018
PARAM.SFO: Various information about the title. This one is never encrypted, although it's always signed. (see: http://www.pdc.me.uk/pbpdocs/#3.2)
PARAM.PFD: Signatures of all the files if the save is protected. The signature method is still unknown (hash-size 0x60).
This file is responsible for making sure the save games aren't tampered with. To prevent file modification of this file and other games files, the cryptographic signatures are inside this file. Some games don't sign their files here though. File size is 0x8000 bytes.
ICON0.PNG: PNG image containing the image to be displayed in XMB.
SND0.AT3: (optional) Sound file to be played.
ICON1.PAM: (optional) Video file to be shown.
PIC0.PNG: (optional) Overlay picture.
PIC1.PNG: (optional) Large background picture.
Some games which are unprotected:
- MotorStorm (protected with CRC32 checksum)
- Call Of Duty 4 (hacked saves can be found on the Internet)
- Battlefield: Bad Company
- Assassin's Creed
- Blazing Angels: Squadrons of WWII
Finally, for PS2 gamesaves they can be converted using the guide here: http://www.ps3news.com/forums/ps3-gu...at-103447.html