Is there any way to do a temporary loan, like when you obtain a library book that's only valid for 2 weeks? This would be a great feature when loaning a book to a friend, like a disposable digital copy. This would not eat into your device count since it's terminated automatically.
While loans are supported by the DRM system, they are not supported for end users to create (has to be one of the Adobe Content Server customers).
I wouldn't think to see this anytime soon, since it is creating another copy of the book, which the publishers are not currently keen on (unless they get paid).