how can I find out if my HP printer is AirPrint compatible?
Is my HP Photosmart C4580 capable of printine from my Ipad?
iPad, HP Photosmart C4580
Unfortunately, it does not appear as if the HP 4580 is AirPrint compatible. Check the list in the link below to verify:
http://support.apple.com/kb/ht4356
If your printer is not on the list, you still might be able to set up printing from the iPad by installing an application like Printopia on your Mac. There is a free trial, so you will know in a few minutes whether or not this might work for you. You do have to have a Mac running on the network in order for Printopia to function correctly.
Printopia - AirPrint to Any Printer - Print from iPad - Print from iPhone ...