Now you're talking. There was this other product only available in Japan that let you transfer memory card files to your PC, but it's quite nice to see something available in the US now. Basically, any game that's customizable would benefit from this. Here's some more examples:
Animal Crossing: Got some extra room on your memory card, and don't know anyone else who plays the game in your area? No problem! Just find someone on the 'net who likes the game, get them to send you their town over e-mail, and go visit! You could have a whole community of people who visit each other's towns, trading neighbors and screwing up the landscape, just as long as people agreed to keep sending files back and forth. Also a good way to trade textures and, to a lesser extent, town songs.
Sports/Wrestling games: Any custom teams, custom players, etc., can now be shown to the world to be admired. I'd especially like to see people take advantage of this for Wrestlemania XIX (bad game, yes, but good customization features)
The Sims/Bustin' Out: Trade your Sims from across the country... on a console this time!
SSB:M: trade your pics, without the need for a fancy screen capture device!
But of course, TimeSplitters 2 really does lend itself to this feature (especially considering how large some maps can get)
So yeah, I'd say it's worth looking into.