Apple does not allow screen sharing the way you might want. We can share a document because we open it inside of our app with a viewer. Apple does not allow apps to share the home screen or other apps inside of another app. It is part of the iOS model. When Apple changes this,w e will totally look into it.
I don't know of any iDevice app which has screensharing abilities.
The sandboxing of apps on the iPad means that one app does not have any
access to a display made by another App. Apple's
tool for remote administration of iPads is the Profile Manager service
that comes as part of OS X Server. You can connect any number of
iDevices to it and use it to install/remove apps, change configurations,
and control what the user may or may not do with their device. Updates
are automatically downloaded over the internet the next time the
iDevice is connected to it: devices do not have to be returned to
headquarters and physically plugged into the server. Check this out for getting more details.