At the moment Microsoft have the strongest xmas line up, but everyone said the same thing about Sony a few years back when Microsoft and Nintendo were coy on what they had to offer until E3, I see no difference this year. I don't see Microsoft cutting the 360's price before NATAL either, they're already the cheapest console.
Resistance 3 and Motorstorm 3 are likely I reckon, maybe the Last Guardian too but non of those are going to be as big as Halo Reach :/. Agent maybe? Suppose they could cut the PS3 by $50 maybe too, I doubt they'll need to though.