Printing from your iOS device can be a little mysterious. If you have a version of iOS that supports 'AirPrint', you've seen the 'Print' button. However, you click it and no printers show up. Well, thanks to a nice little exclusive agreement with HP, only select HP printers get the privilege of being able to be printed on. Apple really blew this one for the consumer.
No worries though.. some third party apps will let you use YOUR printer as long as your Mac is up and running and you have a printer(s) connected to it. .
First up is Printopia, from Ecamm. This is a great app offering more than just printing to all of your printers, it can also print a file to PDF, send it to your Dropbox, Evernote, or your Mac. You simply install the $20 app and it goes into your Mac's control panel and is instantly working. It's a breeze. I wasn't able to fully test it since my 7 day trial expired before I could write the review. Still, a good option, and I've read glowing reviews about it. Sadly, they didn't respond to my NFR request, so I couldn't give it a good look. Originally version 1 of the App was $10. Version 2 upped the price to $20.
If FREE is more your style, and you only want to print to your printer, then all you need is AirPrint Activator from Netputing.com. This is a cool little app that will enable a Mac with OSX 10.6.5+ and iTunes 10.1+ feature to print to your printers that are connected to your Mac. Install this little app and you can print to any of your available printers.
Works great, and it's FREE. Just be sure to install the proper version for your OS. AirPrint Activator 2 (beta) is for OSX 10.5, 10.6 and 10.7 (Lion).