With the filter pipeline in XPS drivers however it would become simpler to do this for any application from inside the driver.
Reversing page order is something the application has to do at the moment.
However, the downside from reversing page order in the driver is that the printer doesn't receive anything until the last page has been spooled.
A better (mechanical) solution is a smarter design of the output tray.
Ps. Nice to see the people we met at DevCon. Special thanks go to John for showing us the way to the Irish pub in Seattle