Rdio (a music streaming service) has just announced a partner video service, Vdio. Unfortunately, It's not streaming, but it would be very cool if this could somehow be integrated into XBMC. My suspicion is that this would be a very difficult plugin to make, but if not, it would certainly be a great way to legally and conveniently watch movies.
Link: https://www.vdio.com/
Link: https://www.vdio.com/