I was looking for this, but only found it within a series of articles in Newsweek where the author basically pokes holes at all the next gen guys and why they are having problems. Taken as a whole, it just seems cynical. but I presume this is accurate:
I don't know if this is worldwide or just US. If it worldwide, then the recent European launch of the PS3 should boost their numbers.
edit: here is a more complete article:
Last Thursday, the NPD group announced videogame hardware and software sales for the month of February. To call the PS3 numbers abysmal wouldn't be much of an overstatement; only 127,000 devices were sold over the four-week period, compared to 228,000 Xbox 360s and 335,000 Wiis. (The rule of thumb for hardware sales during the non-summer, non-holiday months is that 200,000-300,000 is solid, below 200,000 is bad, and above 300,000 is quite good.) On the software side, five of the top ten best-sellers were for Xbox 360, three for Wii, and none for PS3.
edit: here is a more complete article: