A couple of items on the list just incase you might've missed his update. A demo and a new arcade title hit the Xbox Live Marketplace.

Content: Puzzle Arcade
Price: 800 Microsoft Points
Availability: Not available in Asia
Dash Text: Puzzle Arcade - the online jigsaw game with a twist! Multiple ways to play, loads of cool features and endless possibilities. Download the full version to experience Xbox LIVE Vision Camera support, multiplayer modes and access to downloadable content. There are no refunds for this item. For more information, see www.xbox.com/live/accounts.  Source

Content: Legendary Demo
Price: Free
Availability: Austria, Belgium, Canada, France, Ireland, Italy, Spain, Switzerland, United Kingdom and United States
Dash Text: [ESRB: M (Mature) BLOOD AND GORE,INTENSE VIOLENCE] Download the demo for Legendary™, a first person shooter where the beasts of mythology have been unleashed on the modern world. Use heavy weapons and special powers to fight werewolves, minotaurs and more in this incredible fight for survival. Source

Also, be sure to check out the Xbox Live top 10 lists for the week of December 15th....all straight from Major Nelson

Xbox 360 Top Live Titles (based on UU’s)
1 Halo 3
2 CoD: World at War
3 Call of Duty 4
4 Gears of War 2
5 GTA IV
6 Dash of Destruction
7 Left 4 Dead
8 Madden NFL 09
9 FIFA 09
10 Fable II

Top Arcade Titles (Full Versions purchased)
1  Super Street Fighter II Turbo HD Remix
2  Bomberman Live
3  A Kingdom for Keflings
4  Castle Crashers
5  Worms
6  UNO
7  Banjo-Kazooie
8  Ultimate Mortal Kombat 3
9  Portal: Still Alive
10  Braid

The above arcade list is based on full versions purchased.

Original Xbox Top Live Titles (based on UU’s)
1 Halo 2
2 Star Wars: Battlfrnt 2
3 Fable
4 Counter-Strike
5 Conker: Live Reloaded
6 Call of Duty 3
7 Splinter Cell Chaos
8 Battlefield 2: MC
9 Star Wars: Battlefront
10 Doom 3

Top Community Games NEW! (Full Versions purchased)
1  Golden Royal Blackjack
2  Snowmans Dilemma
3  Word Soup
4  Weapon of Choice
5  Tower Revolution
6  World Molder
7  Couples Sudoku
8  Petank Party
9  sin(Surfing)
10  Classicard