I've gotten the payment system to work, except I don't know how to
validate the response. Please see line 53,
http://pastie.org/596506
Hpricot grabs any incoming XML, and pretty much seems to do all the
work. (I don't know how it does, but it does.)
Good news for me, I have a cofounder for this site, and partner in
general. He's working on this ticket now, but I'd like to ask if this
is something more trivial than involved, so I can ask him to work on
something more fun.