In the console market, the PS2 won the December battle, slightly edging out the Xbox 360. Many are surprised by this due mainly to the fact that the PS2 is now six years old. However, price and game library really do matter, crazy, I know.
The DS and PS2 are both $130 and represent the largest library of games for the handheld/console market, respectively. Not everybody can afford a $250 Wii, much less a $400 Xbox 360 or $600 PS3. Add in the cost of peripherals and you'll see why the self-contained DS, and the inexpensive PS3, did so well.
To break this down even more, I think we're at an interesting tipping point in gaming. Video games are becoming more mainstream resulting in more and more consumers wanting to get into gaming. As more and more "non-gamers" do so, the market for horsepower driven ultra-machines dwindles. Let me clarify that...the percentage of the gaming market wanting horsepower dwindles.
The larger gaming public, the watered down version, if you will, wants value and bargains, ie, the PS2 and DS. Many of these people haven't played a video game in years, if at all, so the graphics of the PS2 are just as "wow" as the graphics of the PS3. Therefore, it's not surprising at all that the PS2 and DS are doing so well.