Full game downloads may soon become a sure thing for the XBOX 360 as bandwidth increases for home users and pricing gets cheaper.
In a quote from Gamesindustry.biz hinting at full game downloads coming soon:
"I think it would be a great thing for this studio to work on. I can't say anything else on it or I might be killed to death."
Currently only older less memory intensive games are available for download as full game downloads would probably take about 6GB of space.