With most console news focused on the newest generation of units, which is composed of the Xbox 360, the PlayStation 3 and the Wii, it's often easy to forget that "previous generation" consoles are still up for sale and still popular among gamers. One stern reminder of that is the PlayStation 2, which has more or less silently continued to be one of the most popular consoles in the world. For all the setbacks the PS3 has dealt with since launch, the PS2 has done remarkably well, and reminds us that Sony certainly can do things right if they really want.
As it stands, the PS2 remains the best-selling console in the entire world. Just recently, Sony hit a milestone with it, selling more than 50 million units in North America alone. The very wide game selection and lower price of the console make it a very attractive option for gamers, which continue to contribute to its dominance. Over 140 million are in the wild today, cementing its position as the number one console worldwide pretty securely - at least for a while.
50 million in North America alone make it more popular than the Wii and the Xbox 360, even if you combined their worldwide sales. That will eventually wane - newer technology will replace it at one point or another - but it seems that for several years to come the PS2 is still on top.