One can interpret statistics in a variety of different ways, but in the end, it's the bottom line that matters.
According to projections by TVG Research , PlayStation 3 sales will outpace Xbox 360 sales by January 2011. You can view the estimated progression chart through the link, and the updated userbase numbers are as follows: since launching in November 2005, the 360 has sold 30.2 million units, and since its launch in November 2006, the PS3 has sold 24.6 million units, which means the rate of PS3 sales is actually faster. If the PS3 does indeed overtake the 360 in early 2011 as projected, that will mark the supposed halfway point of the PS3's 10-year lifespan (as Sony keeps insisting it is). If you factor in future price cuts, plus the arrival of the new motion sensing technologies for both systems, the sales rates may alter accordingly. For our part, we have to consider that the 360 had one whole year without any competition whatsoever, and the PS3 still had to deal with a rookie year that suffered from incessant negative press and low overall sales. Given the momentum acquired since then, and glancing down the road at the exclusive blockbusters and the obvious chance of a price cut, it's tough to disagree with TVG's estimates.
But who knows? Maybe Natal will be as popular as the Wii. Maybe the next Halo will single-handedly keep the 360 in the lead. We can't predict the future.