Tim has pretty much written an entire essay on the topic of AirPrinting, leaving little room to add further information.
The only thing I would like to mention is, that instead of connecting USB-printers to a PC/Mac, they can also be connected directly to a router/access point if these have a USB-slot, thus circumventing the need for an always-on PC.
An Airport Express in conjunction with the iPad is a great device, as the APE shares the USB-printer as well as speakers in the wireless network. I have yet to figure out how to print from my laptop, but the iPad prints perfectly via Print'n'Share to a USB-printer connected to the APE.
I have an airport express with a cannon ip4300 attached via USB to it. I print wirelessly from my mac, but have no idea how to achieve this on my iPad. Any chance of a step by step guide for an idiot?!Originally Posted by DontUnderstandMyIpad