It would be very cool if prince could generate PDF forms using regular html forms or using the (much nicer, but not widely supported, yet - but I think it's the future!) XForms standard.

The ability to then submit the output of the form as xml would be really helpful.

I know, I can do this with Adobe Live Cycle server, but that costs $40-50k US. But I could afford the ~$4k that Prince is charging...

It would be very cool, yes

Supporting HTML forms and the new Web Forms specification developed by the WHAT-WG (Web Hypertext Application Technology Working Group) is definitely on our wishlist. Not something we can implement overnight, but one day