According to a recent statement made to GamePro, Sony has said the currently slow-selling PS3 isn't cause for concern. As they say, this endeavor is a "marathon" and not a "sprint."
"We developed the PS3 as a hardware that lasts for decades and believe we are in a marathon rather than a sprint," said company spokesperson Nanako Kato. "With that said, SCE will accelerate the expansion of the PS3 platform over the next several months by offering a rich lineup of attractive software titles and pursuing own promotional activities as a platform holder."
Kato elaborated a bit on those promotional activities, saying they are in the process of increasing demo space at retail stores. They also plan to propose joint advertising with third-party developers (which is probably a darn good idea). The recent numbers aren't too bad, either; 1.8 million PS3 users have registered on the PlayStation Network, in comparison to the 6 million registered with Microsft's Xbox Live. However, the 360 has been out for 19 months in the U.S. while the PS3 has only been out for a little over 7 months, so that puts things in perspective.
All told, Sony has sold 3.6 million PS3s worldwide, but you have to take into account that it has only been available in Europe since March. For the time being, Sony seems satisfied with the PS3's current position.