I saw that article too..on yahoo. I think they are referring to data through February when PS3 was just over 1 million in the Americas, and around 800k in Japan. This would be before March NPD and Europe's launch. March was definitely the PS3's biggest month for a while - since they likely went from well under 2 million sold to very near 3 million sold in just March (probably went from 1.6 million to 2.8 million worldwide).
If sales stayed where they are now..(sales, rough number of weeks/month) ~ monthly sales
PS3: (11k x 4.5) ~ 50,000 per month in Japan (20k x 4.5) ~ 90,000 per month in the USA ~ 60,000 to 80,000 for the rest of the world?
That would be 200,000 to 220,000 sold per month for most months, putting March at 6x greater sales than May (roughly). April likely will have higher sales than May though, with Golden Week/PS3 Eurolaunch madness into mid-month. April will probably have sales of 325,000-350,000 for PS3.
360 for comparison, seems to do 225k to 275k just in the Americas most months, with another 20k for Japan and probably another 75,000 to 125,000 in the rest of the world. 320,000 to 420,000 per month on average.
Wii is the most fluid it seems, since the 'launch' type sales have not died yet (Average launch months 1 and 2 together - divide by 2. When sales are lower than that number, launch sales are gone, I'd say there is a 5% fudge factor to account for NPD's imperfections.)
For Wii, that number is..540k for month 1 and month 2. 270,000 is the needed number for me to consider it in 'launch' demand. January - Yes. February - Yes. March - I say yes, even though sales were 259,000 because it is within the 5% fudge factor, and supply was constrained.
Compare to PS3. Month 1 and 2 averaged sales - 343,000. 171,500 is the needed number for me to consider it 'launch' demand. January - Yes. February - No, sales were not supply constrained and sales were not within 5% of 171,500 (around 163,000+). For added confirmation, weekly sales rates dropped in March.
With that said, Wii sells around 60,000 in Japan/week..about 275,000 per month. In the Americas, sales are higher, more like 325,000 per month (over 70,000 per week on average). Nintendo is kind of shafting Europe right now, since they sold 800,000 in December but have only sold another 800,000 since. That is roughly 45,000 sold/week, around 210,000 per month.
So..from what I can tell:
PS3 Monthly sales post April: 200,000 to 220,000
360 Monthly sales: 320,000 to 420,000
Wii Monthly sales pre capacity increase: 780,000 to 840,000 (Iwata says supply will improve in May, I guess if the production went up in early April, it takes some time to make Wii, then to ship them to retailer distribution centers, then the retailers themselves...I think it will show up this week in Japan for anticipation of Golden Week and then the next week around the world).
Best case scenario for Nintendo: At the these rates Wii could pass 360 in mid November. But, Wii sales sales capacity will likely hit 1.2 million (Nintendo has claimed they are already making 1 million per month in 2007). At those rates, (assuming immediate increases starting now), Wii would catch up in early September. However, with big 360 games coming out throughout the year, I suspect that pushes the date back 4-6 weeks, when 360 sales are much closer to Wii worldwide sales. So I'm going with November 7, 2007 as the day you will see Wii in first place on the front page.