Christmas gets bigger almost every year in the gaming division. Even if this one is huge, the next one, or the one after that at least, will outsell it.
With lack of WW monthly, I'll use NA monthly and Japan. But anway, we know Europe is growing bigger every year.
We do not have that much data, and I'll start were I find it reliable, so in 2004 for USA. December.
Software: 12M (Alert! Totally incomplete)
I can't really say that proved anything, but I'll leave it there so you can see that it hasn't been such a great improvement YoY.
Still, christmas second/third year should be bigger than first/second.
This year; Wii has had a huge line-up and there looks to be more to it. Without huge 3rd party support later on, I'm not sure it will be beatable.
X360 had the same as above last year, and I doubt this year can top that, but it looks like the line-up will be so close that the sales might be about the same.
Ps3 had a pretty bad line-up last year, but this year it is on par with the X360 one, albeit, I expect them to have bigger next year.