2007 had the holy trinity of Bioshock, Halo 3 and Mass Effect.
2008 had the price-cut.
2005/2006/2009 not so special.
2010 has the software (Splinter Cell, Mass Effect, Alan Wake, Fable and Halo) and the price-cut... and Natal. It's going to be a mammoth year; perfect antidote to the Slim.