Just to mention that John Lewis are selling the HP CN245B Printer for £39 - I paid £59 for one 6 weeks ago (grrrr...). It is wireless and has ePrint technology and printing from an iPad was easy to set up. For the money it is excellent value.
I have tried with Pages but although everything seems to be in connecting [printer identified by iPad - says its 'Contacting Printer...'] nothing gets printed.
Looking around other users seem to have the same experience. Lion looks as if its the issue.
I have tried it with my iPod touch and it seemed to work fine the first time I tried it. Unfortunately when it got to the point of actually printing I had an error message saying that the photo was the wrong size for the paper selected, but there was no way to adjust either the paper or the photo. The next time I tried nothing at all happened even though it appeared to have identified the printer. Just as Mark has described.
I have just tried again with a test document produced in Pages and it worked perfectly. My printer is a HP Photosmart 6280 all-in-one.
David Fleetwood 