Sony's PlayStation 3 debuted on November 17, 2006 to lines and crowds braving the weather to get their hands on the successor to the wildly popular PlayStation 2 (which sold over 100 million units) and PSone (the original PlayStation), the console that put Sony on the map in the gaming industry. The PS3 had a slow start, largely due to lack of compelling or exclusive games and a high price ($500-600), but Sony hopes to repeat the success of its last two systems over its proposed 10-year lifespan.
Despite initial criticisms, PS3 gained some momentum from several perks and more focused marketing. The unified minimum (and somewhat user-serviceable) hardware has simplified development (like wi-fi and a built-in hard drive) and every system doubles as a Blu-ray player (the cheapest on the market in its the first year). While PSN is not as feature-rich as Xbox Live, it's adding new content all the time, and the free price tag definitely has wide appeal.
Other contributions outside of gaming — such as being a part of Stanford University's Folding@Home protein folding research project — have given it appeal and cultural significance beyond just being a high-tech toy. Gaining some high-caliber exclusive titles such as Metal Gear Solid 4, Killzone 2, Uncharted: Drake's Fortune, MotorStorm, Ratchet and Clank Future, Resistance 1 and 2, Gran Turismo 5, and God of War III has helped fuel the PS3's growing popularity as well.
The emphasis on casual games on the Wii and high hardware failure rates of the Xbox 360 are two of many factors helping the PS3 gain ground on its competition.