Skorj: I suppose you could probably do it with any of the other colour Polaroid pack films and possibly the Fuji ones too, although I'm less convinced about the latter. Either way, it's all about getting the prints wet enough to manipulate, but not so wet that they disintegrate. The good news is that once they're wet, they can be manipulated multiple times for around an hour. Gives you plenty of scope for trying different swooshes and swirls, scanning the result and then trying again. My reservation with the Fuji films is that - based on my experience - they might start to lift off from the backing card right at the point where the emulsion is wet enough to manipulate. They seem to float off the backing really easily whereas the colour Polaroid pack films will allow themselves to get absolutely sodden and yet still cling to the backing card to some extent.
Jonas: Portraits? Might work well. I'm certainly going to try this technique out on a few of my less successful prints and see where I get to. The thing I noticed about these two prints is that the dark areas didn't lend themselves to being moved about, it was only the lighter areas...so it might not be too good with prints which don't have large light areas. Although having said that, if we're talking protraits it should work on light-skinned faces well enough