I have tried a couple times to see how Moodle (1.7) and once some quiz questions I have would look on my Palm Treo 600 (not exactly state-of-the-art) using its built-in browser.
The first thing I noticed was that the "PDA theme" that is included with Moodle was not at all good (at least for my treo). I think I've seen something in a forum about it only being an early test that no one has maintained it. (There are some Moodlers in Japan that have been doing some stuff targeted at quizzes on Mobiles, but I haven't been able to check it out.)
Swedish letters åäö were mangled.
But the questions I tried worked in a usable fashion, in spite of my having the WOOD theme. The TREO has a touch screen which allows a mouse like navigation possibility. But I think I could even navigate with the arrow buttons. I tried multiple choice which worked well and showed feedback nicely. I think I also tried short answer. (If I did, it worked. If I didn't, don't know