I reckon '08 has been one of the best years in gaming in a long time, even after the relative awesomeness that was '07, and the dreck that was '06. In fact, I think I've spent more money on games this year than I have in the past 3, so I'm kind of hoping for a quiet year next year 
So, my top 10 in no particular order. Note that some of these games were released in 2007 in North America, but only in 2008 in Australia. So there.
Valkyria Chronicles
Yakuza 2
Shin Megami Tensei: Persona 3
NiGHTS: Journey of Dreams
Far Cry 2
Left 4 Dead
Braid
Endless Ocean
SEGA Superstars Tennis
Viking: Battle for Asgard
Fire away, kids.

So, my top 10 in no particular order. Note that some of these games were released in 2007 in North America, but only in 2008 in Australia. So there.
Valkyria Chronicles
Yakuza 2
Shin Megami Tensei: Persona 3
NiGHTS: Journey of Dreams
Far Cry 2
Left 4 Dead
Braid
Endless Ocean
SEGA Superstars Tennis
Viking: Battle for Asgard
Fire away, kids.