The "Northern California Digital Library" (http://califa.lib.overdrive.com) already loans out digital books (read with Adobe Digital Editions software) to patrons of many Northern California library branches. The system enforces limits on how many copies of any book can be checked out and so is just like a library. It's convenient but the selection is, for now, limited. I've found some good books there and really prefer this to going to the library.

And the DRM appears to just work. I don't mind this model for books, music (I'm a Napster-to-Go subscriber), and when the first viable stream-for-rent system for movies arrives I won't mind that either.