One of the reasons I play the PS3 instead of my Xbox or even the PC sometimes is because you don't have the cheating save files issues that are rampant on the Xbox community. Sorry Xboxers (I am one ((not cheater

))) I hope they don't put out any kind of construction tool that allowes you to mess with your save files, or the playing of the game.
If they make it an actual part of the game, inside the game, then ok. But a stand alone alteration tool, no. I'd rather they dump the Havok engine and release playable games instead. If Red Dead Redemption can be a flawless game, so to can be Fallout.
I've been playing games with cheats and liars since before there was an internet. One thing I like about the PS3 is the pretty much cheater free multiplayer landscape. Sure there are glitchers and such, but again that's flawed game design usually and hopefully fixed as they come across the exploits. Save game and Game Data corruption is much different and not missed at all by me.
Fallout may not be online/multiplayer, but allowing the player editing of game data or save files will not be limited by that if it's allowed.