Well, that's what the PS3 isn't doing, at least in North America according to NPD.  The March numbers are out -- check these threads for actual numbers: (QT3) (NeoGAF). 

Yet another month where the PS3 failed to move more units than the Xbox 360.  Time will tell whether releases in the Fall (woo, Ratchet & Clank) and international sales will save the PS3 but right now it's looking like that particular matchup is a blowout in favor of the 360.

Of course, the Wii outsold them both.  However, while 360 vs Wii was about -100k in February, it was -60k in March (a longer month, to boot).  The Wii's supply issues continue to keep it from really capitalizing on the mindshare advantage it has right now, and by the time they sort things out some of the 360 powerhouse releases will be fast approaching (or already arrived): Bioshock.  Mass Effect.  Forza 2.  Halo 3.  I'd count GTA IV in that set too until some compelling reason to play GTA on the $200 more expensive console without exclusive DLC is announced.

Obviously I'm biased (both as an MS employee, and because Ensemble is developing Halo Wars as a 360 exclusive), but I still think things are pretty grim for PS3 no matter how you slice it.  Empirically, my home use is about in line with these numbers: the 360 and the Wii get plenty of play while the PS3 is pretty much just a fancy box for playing PS2 games and doing some protein folding...