Did you compare to how large/small 360's shelf space was around this time last year? Probably no bigger because there just wasn't all that many games out ofor it.
That makes sense - you can't fill shelves up with absent game boxes! Though the game situation is better than XB360, isn't it? Here's a list of what Play has available (in stock or awaiting stock, and no preorders)
Avatar: The Legend of Aang
The Ant Bully
Barnyard
Blazing Angels: Squadrons Of WWII
Call Of Duty 3
Cars: The Movie
Dragonball Z Budokai Tenkaichi 2
Eledees
Excite Truck
Far Cry: Vengeance
Gottlieb Pinball Classics
The Godfather: Blackhand Edition
The Grim Adventures Of Billy And Mandy
Happy Feet
Heatseeker
Ice Age 2: The Meltdown
Kororinpa
The Legend Of Zelda: Twilight Princess
Disney's Meet The Robinsons
Madden NFL 2007
Marvel: Ultimate Alliance
Medal of Honor: Vanguard
Metal Slug Anthology
Need For Speed: Carbon
Open Season
Prince Of Persia: Rival Swords
Rampage: Total Destruction
Rapala: Tournament Fishing
Rayman: Raving Rabbids
Red Steel
SSX Blur
Sonic and the Secret Rings
Spider-Man 3
SpongeBob SquarePants: Creature From The Krusty Krab
Super Fruitfall
TMNT: Teenage Mutant Ninja Turtles Limited Collector's Edition (Wii)
Tiger Woods PGA Tour 07
Tony Hawk's Downhill Jam
Wario Ware: Smooth Moves
Wing Island
World Series Of Poker: Tournament Champions
There's more than just party games in there, which is what many asociate with Wii. It's a good question if these non-motion-heavy titles are getting the sales though. Do Wii owners want anything other than the simpler games?