You could load movies onto your phone. Or you can go to m.mSpot.com on all four major carriers using most smartphones to access $5 movie rentals.
You can expect movies a few weeks after they arrive to DVD from current participating studios Paramount, Universal Pictures and the Weinstein Company. The rentals are good for anywhere from 24 hours to 5 days.
Streaming a trailer, the quality wasn't super high (framerates, especially, took a hit). Plus, with iTunes rentals running only $4, it's tough to imagine mSpot taking over (iPhones, at least) entirely.