Interestingly, apparently the Guest account only has to be active when the AirPrint service is started. After the service starts, I can disable the Guest account and continue printing. No substitute for having real userid / password authentication in place (like iOS 4 did) but better than leaving Guest active all the time.
The setup worked very well as I posted above in the end of January. UnfortunatleyI had to change DSL-modem and router a couple of days ago. From a Zyxcel-modem and Netgear WNDR3700 to a Thomson TG789vn (router-modem combo).
Now the printing only works if I turn of the firewall in the Win7-computer where I run the Airprint service. To my knowlege I didn't change anything in the firewall. Anybody out there who can give me some advice how to set up the firewall (f-secure 2011) in a proper way? Or any other tip.
If I restart the bonjour and airprint services the printing works for some minutes. I have also tried to install FingerPrint and it has the same behavior.
I am not sure this is the solution. It does work for me. It may help others as well.
I was taken by surprise too that the new IOS did not support printing on my printers any more. The father of my wife bought a HPprinter with WiFi capabilities. He did not realize this printer was not an Airprint printer. So he created a challenge for me: How do I print on a printer without a PC running.
I found the tool HP ePrint in the AApple Store. After installing this on his and my Ipad I was able to print email and other documents on the printer.
Coming home I found that I was able to print on my printers as well. I had not tried for a while and there had been an update from IOS already. So I do not know if this solution was created by using a new version of IOS or it has been created by the app from HP.
Please let me know when someone tries this and resolves the issue as well.