It's a Halo demo trailer (an exclusive 360 system seller game) being played on a Playstation 3 Demo booth. Irony at it's finest. A game PS3 will never have that Sony would most certainly want being a demo on a PS3 demo station instead of any actual PS3 titles
It also comes at a point where PS3 has had several of it's "big exclusive" titles get completely slammed by the gaming reviewing community. Which would really make most demos of any big PS3 titles lack luster anyways..

It's humorous to anyone that enjoys irony and likes 360 over PS3. Usually irritates the PS3 supporters though...