At the Clever Dog Lab in Vienna, researchers use a "computer-automated touchscreen testing procedure for studying learning, social, and physical cognition in the dog."
I learned about this in a radio documentary called King Solomon's Ring from CBC's Ideas show (you can find the audio here: Ideas podcast or on iTunes). The documentary was about ethology -- the study of animal behavior, and about Konrad Lorenz, one of the field's founders. King Solomon's Ring is also the name of a classic book by Lorenz.
The dogs use their noses to activate the touchscreen, and apparently dogs do it well but it takes some instruction. I'm guessing it's a little like touchscreen usability studies with humans, but with more screen wipes. From the page for dog owners interested in participating:
We employ the computer-automated touch-screen testing procedure to study physical cognitive abilities (knowledge of how the physical world works). But first of all, it is necessary to find out whether dogs behave similarly when they are confronted with a similar problem in reality and on the screen.
From previous studies we know that dogs are able to find a hidden object even if considerable time has passed since they witnessed the hiding event. Dogs also show typical errors in their searching behaviour when a human experimenter hides the object. Thus, in this project, we want to investigate whether dogs can solve a hide-and-seek task on the touch-screen and whether they have similar error patterns on the touch-screen as in reality. I test the dogs’ performance in ‘real’ and ‘virtual’ (Touch-screen) conditions. In the virtual condition, I test them either with or without the presence of a hiding agent.
Dogs need a considerable amount of time to learn to work with the touch-screen. For optimal learning performance they and they owners should visit the lab at least once a week. A training occasion consists of 2-4 sessions. Each session has 29 trials. The auto feeder gives a dog a dry food pellet for every correct trial so a dog gets maximum 120 pellets per training occasion (altogether a small cup of dry food). A training occasion for a dog last from half an hour to one hour.
You can see a video of a dog doing a test at LiveScience, from a 2007 article: Dogs Do Well On Computers.
The lab has a web page showcasing some of their most enthusiastic study participants: Computer Freaks.