I think this is because most XBOX games sell pretty good the first few weeks and then have little to no sale (thus the sharp decline in prices only a few months after release). Publishers think this is a trend and tend to be wary of products that don't sell immediately.

However, I think the reason XBOX games tend to perform they do is because most of XBOX users are hardcore gamers who want to play the game as soon as it comes out.

I am hoping Prince of Persia has legs (it has sold ~900 thousand copies across both platforms) Assassin's Creed has sold about 7.5 Million copies (4.33 XBOX 360, 3.133 PS3) but its initial sales were not that strong either.

Ubisoft is a great developer but they need to concentrate on making the epic games like Assassin's Creed, Splinter Cell and Far Cry instead of PoS.

PoP is a lot better than FarCry 2 imo.

For me it's one of the best title released these holydays...

Assassin's Creed sold over 1 mil after first week and break 2 mil after second week. And it's a new IP. If that's not a strong start, I'm not sure what is.

Ok, time to chime in here regarding recent talk about innovation:
1. These are GAMES produced to sell, and be consumed by customers and provide them forms of entertainment. They are NOT art projects meant to change the world, but to entertain. Game companies are not around to get pats on the back, but to sell merchandise, and make money. You are in the business to make money.
2. There are several reasons why innovation is important:
a. To solve problems in a given area no one has accomplished, so that you can reuse it. Being able to solve the problems with jumping from a 3D perspective would be a BIG help. Someone who can figure out how to get RTS to work on consoles would also be innovative and do a large favor for everyone.
b. To provide surprise and novelty that keeps gamers entertained. Doing the unexpected COMPETENTLY is important to keep games entertaining.
c. To service certain niches that were untapped. This means doing stuff like Nintendo did with the Wii, to make bowling and so on more immersive, and accessible.  This can be viewed as being first to market with something.

3. Companies that try to be innovative try to seriously give their games more time, and see if they have legs, and view ther first game as one in a start of a franchise.  You look long term with sales and hope your initial title sells enough.

All and all, you don't innovate for the sake of innovating IN THE MARKETPLACE. Competency is superior to innovation. However, you need to advance the art, in order to prevent the masses from getting bored and moving on.