Gamestop might be king of the hill today, but it could be Tower Records tomorrow. After its E3 press conference, Microsoft announced during a press lunch that full game downloads will be available on-demand starting late summer. Those games include Bioshock, Assassin's Creed, and Oblivion, all full-disc experiences.
On August, 30 titles will be available at the start of the service. It's not clear yet whether these will be "classic" 360 titles or will also expand to cover newer holiday releases. Considering the bandwidth drain this will already cause, it seems likely the supply will be (for now) lower-demand titles from the past.
For these on-demand purchases, direct credit card charges will be accepted in addition to Microsoft Points. Games will be priced to match retail, meaning that--for now--no "disc-free discount" will be applied. But it does seem that, together with the, our is getting closer and closer.