Hey, I'm working on something like that for this year's NANY, dubbing it AdaptiveDrive. I think I'll get the teaser on shortly, but it should create batch files that work as dynamic shortcuts. I was thinking it would have 2 types - static shortcuts and portable shortcuts. The static shortcut idea is what I think you're after.
Clarify : You want one shortcut to point to (e.g.) FireFox Portable, no matter what drive you put in?