Nintendo will only showcase the latest Mario title at the event.
http://www.nintendoworldreport.com/newsArt.cfm?artid=20545
A special Nintendo Jump Festa Page has confirmed that Nintendo will only have one game to demo at the event: New Super Mario Bros. Wii. Visitors to Nintendo's booth will be able to try out some of the game's levels with up to three other players, highlighting the game's multiplayer features.
In addition to the demo, Nintendo will be holding a special Coin Battle Tournament. Winners will receive a prize that has yet to be revealed by Nintendo. Finally, attendees will also receive special items just from visiting the booth.
Jump Festa 2009 will start next week on December 19.
