Hmm, what does the gap change look like percent-wise? The time of year impacts total sales for both platforms, and consequently the gap is impacted, so a percent-wise comparison would be more useful.
Personally I expect it to start outselling PS3 when it gets a price cut. Which should happen in the second quarter unless MS decides to hold out for Natal.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.