Check out this link that discusses a new IPad application.
Experience the Art and Craft of Letterpress Printing on your iPad
LetterMpress™ will be a virtual letterpress environment—released first on the iPad—that will allow anyone to create authentic-looking letterpress designs and prints.
The design process is the same as the letterpress process—you place and arrange type and cuts on a press bed, lock the type, ink the type, and print. You will be able to create unlimited designs, with multiple colors, using authentic vintage wood type and art cuts. And you can print your design directly from LetterMpress or save it as an image for import it into other applications.