Just a quick note for anyone not able to find any details about why they still can’t print from their IOS4.2 devices. It seems that a few much awaited features had to be (hopefully) temporarily crippled to make sure IOS4.2 was released sharpish. Gruber has some more on that.

Anyway, the following is a list of currently supported printers from Apple:

Works with AirPrint-enabled printers.

AirPrint works seamlessly with a new generation of wireless printers from HP.

AirPrint-enabled printers

• HP Envy e-All-in-One series (D410a)
• HP Photosmart Plus e-AiO (B210a)
• HP Photosmart Premium e-AiO (C310a)
• HP Photosmart Premium Fax e-AiO (C410a)
• HP Photosmart e-AiO (D110)
• HP Photosmart eStation (C510)
• HP LaserJet Pro M1536dnf Multifunction Printer
• HP LaserJet Pro CM1415fn Color Multifunction Printer
• HP LaserJet Pro CM1415fnw Color Multifunction Printer
• HP LaserJet Pro CP1525n Color Printer
• HP LaserJet Pro CP1525nw Color Printer