As @byn's husband I can assure you that her freewrites come out like magic. It's truly an amazing thing to watch happen. We've taken to calling it 'word vomit' when she gets on a roll :) It's a talent that I surely don't possess.

I think you're right though that a freewrite can take whatever form that you want. Poetry, prose, fiction or non. I've told her a couple of times that I should video the process some day because I don't think people would believe that she writes these things in five minutes with no forethought.