Well im guessing you could but only if you need to re-partition on-the-fly. Even without bootcamp, you could install multiple copies of OSX onto different partitions or drives. The Bootmenu was built into your Mac anyway.
Ive never looked, but if there are non-destructive partitioning tools available, it might be better to go that way than using bootcamp which was really intented for windows.
What I'd like to do is overwrite an existing copy of Vista with another copy of OS X for some testing. How would I go about doing that? Also, I might need to make that partition a little bigger. How could I do that without screwing something up?