I agree in regards to North America specifically (which I believe was the primary focus of your post). The ps3 currently has a great image, a great price, great marketing, and a great line up for North America (even if you only look at Uncharted and God of War), and shortages are definitely preventing Sony from truly capitalizing on this potential. Without these shortages, Sony could've possibly come ahead of the 360 even in January, despite Mass Effect 2.
The ps3 was holding steady at 90k per week in NA throughout January, most likely with a consistent sell through of Sony's weekly shipments, but this past week it dipped down to just shy of 80k. Given Sony's comment on the issue, things could get even worse. (Though our numbers may have been a tad high, given the results of NPD - we had ps3 13% higher than NPD for the US.)
The only issue is whether or not potential customers are buying 360s instead of ps3s as a result of these shortages. I doubt that to be the case, especially if it's something like God of War that's propelling people to finally pick up a system.
I do wonder what the ps3's current ceiling in NA would be without supply issues, though. It's possible it'd still be topping 100k weekly, given how bone dry stock is in southern Louisiana. Of course, the current demand (which is quite high in my area) could simply be pent up demand that'd dissipate fairly quick once supply normalizes. Let's say the ps3 would normally sell 95k a week, but only gets shipments of 90k per week. By the end of that month, demand would seem incredibly high (20k people looking for ps3s on top of the normal 95k/w!), but would go back down to 95k/w with just one large shipment.