For the limited amount of printing I do from my iPad, I have been using AirPrint Hacktivator. It works fine for me, but you do have to have your regular computer on and awake for it to work. It also installs on your computer, not the iPad. I don't remember where I read about it, but there is a link to learn more.
http://www.wired.com/gadgetlab/2010/12/ipad-iphone/
I just checked, and Apple made them take it down, due to Apple code or something like that. The new app is called AirPrint Activator.
http://netputing.com/airprintactivator
Jackie K.
Moorhead, MN