Here's what I did all day:
CSS totally rocks. In particular, @media print. We have these fancy paper+label combo things where we print the packing slip on top, and the addresses on labels at the bottom, and CSS lets us absolutely position elements right on the labels. I was afraid I was going to have to write some stupid win32 app ... but nope: just HTML+CSS.
Note: the /store/ isn't officially launched, so don't go spreading the word too far... we're not announcing it until tomorrow afternoon or so after we're sure it's all working, then it'll be better linked with the rest of the payment land. But 50 orders have already gone through with no bug reports, so it's probably safe if you want....