You mean "taking away market from the PS2"? Judging from the current sales, PS2's life expectancy is well beyond 2009.
No... Again, what I mean is casual gamers who bought a PS2 after its price dropped to $200, which was about 5 years ago. These are the people who haven't bought GTA, MGS, FF, DMC or similar hardcore games, and they're probably a quite large percentage of the ~110 million users out there.
They are probably looking forward to upgrade to a new console within a few years. Probably get a PS3 once it's cheap enough... but suddenly they notice the Wii in shops, with a radically new and totally fun controller, and new kinds of games as well as some of those that they've played on the PS2. And it's cheap enough as well at $250, and they've had the PS2 for long enough to get bored with it anyway.
So what I mean is that the Wii is taking away the future market of the PS3 today.