Digital delivery of games and gaming content is the inevitable future. But how prevalent is it in the present? The NPD Group estimate that, as it stands, digital downloads on a console are doing... OK.
The retail tracking firm reckon that, of all Xbox Live "Gold" subscribers, 18% of them "regularly download from Xbox Live Arcade". When it comes to the PlayStation Network, things aren't quite as big, as only an estimated 10% of account holders "regularly buy digitally from Sony's PlayStation Network".
It's important to note that this survey isn't counting somebody who bought a single copy of Street Fighter II over XBLA and left it at that. It's tracking those who buy, and buy often.