Yep, but you may want to work over FTP.
So lets say, you have james in England, and his best buddy Raoul in america, lets say there working on a game and there now onto level 8 and they want to get a 10 level demo out within the next two weeks, so they want to work on both maps with each other, so they both work on one toghether than do the same with the other.
So they also have a website server which they both have acsess to, meaning they can upload there map there and the other can download it(*.fpm).
Simple really... And there are applacations that allow you to see and do stuff on other's desktops, one of these is Team-viewer 4, brilliant app, I reccomend it to anyone who wan't to do somthing like this.
"Your greatest teacher is your harshest critic"-'Butterfingers'