Now that Safari, Mail and Photos have the ability to print after updating to iOS 4.2 on your iPhone, do you need an AirPrint-enabled printer to use the feature? The answer is no. Several programs have already been released for Mac and Windows that will set up your existing printer to work with AirPrint over a Wi-Fi network.
Once installed and properly configured, your printer will appear on the iPhone whenever the print option is selected from within an app. Printers that are connected to your computer can be used with AirPrint and the following programs: