hmm sounds interesting......does this means you can have mac OS as your primary OS and then have XP running in a mac window? you know so you can drag and drop/rewire etc between them?
Nope, unfortunately (that'd be quite cool if you could). There is an emulator that does this, but it's not as swift as a bootcamped XP installation, and not free.

Bootcamp's relationship between the OS's is probably best thought of as follows: Once bootcamp is set up, both OS's have a control panel setting called "Startup Disc", and you can choose Windows XP or Mac OSX in that setting. When you next start up the machine, it boots into whatever OS you've set there. They otherwise don't share files or interact at all, except that the bootcamp setup software on the OSX installation can be used to re-setup, repartition or delete windows if needed.