AirPrint is nice
You can set up AirPrint with about any printer. You just need to install Bonjour Print Services (you'll have to do it manually), that'll be on their site under support section and then downloads. Once that (and obviously Bonjour) are installed, add your printer to the Bonjour Print Services config thing. Now you should be able to print to any printer wirelessly using your computer as the host/proxy. I suppose the difference that makes a printer an "AirPrint" printer is the ability to go directly from device to printer, without the desktop as an intermediary— though, I think that most people that have a printer already have it added to their desktop (and want it there).
Since this is true of me, it's not of importance or necessity that it goes direct to the printer, and so this solution was perfectly fine for my use (and I suspect will be perfectly acceptable and transparent to about 90% of people).
Point: before going out and buying a brand new printer assuming your printer can't handle printing from iDevices, understand the implications. Unless you have a specific need or reason to cut out the computer and do direct device to printer printing.