Sorry to hear you're having that trouble, Nick. I haven't personally tried using an iPad yet, but we can see if we can get you a response regarding the issue. Do you have any more details, so far as any error messages, unresponsive buttons, etc.?
The main image uploader uses Flash, which the iPad can't support, but there is a 'simple uploader' you can use to upload your art: http://community.art-is-fun.com/photo/photo/new
Let us know if that solves the problem!
Speaking of the iPad, I would like to use my iPod Touch (which is like the iPhone) to upload art but I get this message: