Demo making is a new(er) market for consoles, in the way of that they are readily now available.
However, demos for games have been around since the PS1 era for consoles - I remember playing tons of great demos (like twisted metal) back in the day and loving it.
It'll take time for developers to make great demos all the time - nevertheless, thus far, the demos have helped prevent alot of gamers from making real bad mistakes (Hour of Victory).
However, there are games like Blue Dragon that have so-so demos (in some people's opinions) that are/should be awesome games.
Either way, I think that creating a real strong demo will be a huge key for non-AAAAA games to do real real well. Oblivion, Gears of War, Call of Duty 2, and a few others never needed demos to do real well. But for lesser known, but great games, they have a chance to do real strongly. Ace Combat 6 is a great example: the demo was well recieved (as far as I know), and managed 500,000 downloads it's first week. For a game like AC6, to a new console, this is real good.
Back from the dead, I'm afraid.
