The PS3 2008 lineup shames all others.
People are ultra quick to judge the HS/R&C/Uncharted combo this fall, adventure games and all with ironically the biggest X360 release destined for 08 being Alan Wake (though potentially Halo Wars in my eyes).
There are at least three PS3 exclusives coming next year that will strike higher than that game, those being Killzone 2, MGS4 & GT5 (the first two will hover around 4-5 million copies sold, GT5 will probably be ~10 million).
Now, we have those three games but we also have a total wild card with LittleBigPlanet. It will sell a million or two guaranteed but it could really really take off. There's nothing like it and it sells itself to people in less than 10 seconds, it will be very interesting to watch.
And besides those, we will have to see if Final Fantasy XIII makes it out, that could potentially make it five exclusive 08 PS3 games that outsell the top selling 08 X360 on their own.
Then besides those we have exclusives like WipEout PS3, White Knight, Socom 4. Those are million sellers. Then we have additional quality titles like inFamous and potentially a Insomniac game and other unannounced Sony 1st party titles (they usually announce them nine months ahead).