I just googled for XBox Live features, and demo downloads seemed the most likely possibility for a single player game (last I heard Larian was still undecided about a demo, but that was awhile ago). If you don't need a Live certification to offer a demo through the service, though, I guess downloadable content is a possibility.
I think DLC maybe coming.
My reasons for this if you look at Fallout 3 they have the Xbox Live logo on the box art, even though its a Single Player game yet they knew they were bringing out DLC.
![[Linked Image]](http://gamersdigart.files.wordpress.com/2008/11/fallout_3_box_art.jpg)
They even put content downloads on the back
My thoughts are there is some sort of DLC planned in the future.
PS.Larian whens the DEMO?