AirPrint is great in theory, but in practice your chances of finding a supported printer in the copier room are roughly equivalent to spotting a yellow-eared parrot in the wild. TruPrint boosts those chances dramatically, adding iOS support for "most" printers that are shared on the network. Unfortunately no actual listing of supported models has been provided, but there's a three day free trial if installed over Cydia so you can try it for yourself -- yes, you'll need to jailbreak first. After that it's $9.99, which is a bit steep, but if it saves you having to wait in just one line at the airport terminal to print a boarding pass it's well, well worth it.
