I would agree with Sean about the use of Webdav. It seems to be the best way of using the iPads with multiple users. If you have a VLE which can utilise webdav shares to store documents (I know StudyWiz does) then it can potentially be a great way to work. You can also use an app called webdav nav. This is more like a browser-based way of viewing webdav shares.

I have experimented recently with the new iBooks author tool for mac and sharing it out using a webdav share which can be accessed via the webdav nav app, potentially allowing pupils to import the iBook I made into their own iBooks library.