A team has got together to create an Iphone app for Moodle. If you have an Iphone are considering getting an Iphone or are just interested you can find out more information from

http://iphone.moodle.com.au/

Update
Another Moodle app MoodleTouch should be in the App store in the first week of April for further information I have listed their site below.

http://www.pragmasql.com/133/section.aspx/81