I have this problem also,
We have an iPad 2, iPod Touch, iPhone 4,4s and iMac.
The printer is a HP LaserJet CP1525nw and is listed as a compatable AirPrint printer.
The two iPhones and iPad 2 were upgraded to IOS6 last week.
We wanted to print something out today and when selecting printer it came up with "No AirPrint Printers Found".
This happened on the Other iPhone and the iPad as well. However all the other devices that were not upgraded still work.
I have upgraded the firmware on the printer to the latest version, however this has not helped. I have restarted all devices as well as my network router multiple times to no avail.
Apple need to provide a fix as this provlem is evidently as a result of their IOS6 upgrade.