At the end of the day it is all about the games.
If you look at the three consoles the 360 has the lion share of AAA titles this year: BioShock, HALO3, MASS EFFECT, Fable 2(maybe), Splinter Cell: Conviction - off the top of my head. Not to mention the apparent enhnaced versions of VF5 and GTAIV.
So far Sony 's european release schedule is looking like a deserted highway. Warhawk and Heavenly Sword seem to be the only exclusive AAA titles coming our way.
The Wii too needs some love, still no release dates for Mario or Smash brothers.
Hopefully E3 will get flesh out the plan of attacks for the latter two, but as it stands 360 is looking stronger games wise.