As an unabashed fan of the angle brackety type things, I’m chuffed to learn, via Norman Walsh, that XProc is now a W3C recommendation. Congratulations to all the people who put in all the work to get it there. Take a look at if if you need to run your XML documents through a bunch of steps and produce a bunch of results (and do other things along the way).
I’ve used XProc in a limited way to run a sort of enhanced XSLT process, and it was slow to get started, but once I wrapped my head around the central concepts, the rest went like butter. Given that the specification provides for making HTTP requests, I’d think it could serve as an especially useful component in a RESTful document publishing architecture. But then, I would say that.