In the latest version of iOS Apple included a new feature called AirPrint. Designed to bring native printing support to the iOS platform it can be found on version 4.2 or later devices such as the iPhone, iPod and iPad. At launch only a handful of HP wireless printers can be used but with the help of this article it is possible to AirPrint to any printer connected to a Windows computer, including Windows servers.
First, enable network printer sharing for the printer attached to your computer. In Windows 7, click on the Start button and select Devices and Printers. Locate your printer, right click on the icon and select Printer properties.
Click on the Sharing tab, check the Share this printer box and then click OK.
If this machine does not have iTunes installed you will need to install the Bonjour Print Service. You can download the file from Apple directly.
After Bonjour is installed, make sure UDP port 5353 is open if you have a firewall.
Finally, make sure the Service Startup selection is set to Auto and click the Start button.
The setup is now complete. Test AirPrint by using Safari and the Bookmark button or in Mail with the Reply button. You will find a Print option in the pop-up menu. Select your Printer and touch Print. You may be asked to authenticate, use your windows account on the host computer.