I wanting to allow people to use an iPad at work, but I want them to only use the application I provide. Is there a way to lock down the pushing of the "Home" button so that they cannot leave the application?
Is there another app that might make this possible?
It's not possible with the iPad itself, and I doubt very much that any app could do this either, but I can't say for certain. Someone else here may have an idea.
Unless you want to jailbreak your iPad (which Apple frowns upon, and it technically voids your warranty), there is no way to do this in software.
There's a very complete discussion of locking down iPads over at this forum, if you want to read about various cases and such, though most solutions are pretty heavy-duty:
http://forums.macrumors.com/showthread.php?t=931043