iOS 4.2 - AirPrint - AirPlay
It all seems to work.
I was impressed that I could set up the HP B110a on my wireless network, update the firmware and print from the iPad without going near a computer. Never mind that I now have an extra printer that I didn't want.
I assume that most apps will be updated soon to support AirPrint.
HP iPrint allows you to control scanning from the iPad. I haven't quite figured out what you can do with the scanned documents yet. Let's hope that they can at least be emailed.
As for AirPlay, I am really quite disappointed that it only works with the very few apps the allow you to choose it for output. Why can't the iPad "desktop" simply be diverted to AirPlay?
I am of the school that detests and carefully avoids iTunes by the way