Below is the list of new content on Video Marketplace. One exclusive is the South Park Seasons 5-8 this week only.

Thanks to The Major for the info.

TV
South Park (Seasons 5 - 8) - Exclusively For Download On Xbox Live This Week
The OC
Laguna Beach (Seasons 1 & 2)
All of Us (Season 4)
New UFC Fights
Robot Chicken (Season 2)
Tim & Eric Awesome Show Great Job (Season 1)
One Tree Hill (Season 4)

Movies
South Park: Bigger, Longer, & Uncut (SD)
Grumpy Old Men (SD)

Trailers
Blades of Glory
Pathfinder (3/1)
Bee Movie (3/1)
Simpsons Movie (3/1)
Fred Clause (3/2)
Harry Potter & the Order of the Phoenix (3/2)
Transformers (3/2)