The timing would make sense.

How hard is it to admit it doesn't work that way? 

LOLz, Sony sure could have said that the reason they weren't selling as much PS3 was because of shortages, and it would be belivable to a certain degree given the fact that the PS3 has allot more new tech in it than the 360, but not even Sony was smug enough to lay this BS on it's conusmers.

 QFT!!!

Perhaps this is a strawman and there's just no shortages.

Here's a likely theory.
MS thought the Xbox arcade would do well.... and it didn't...
Anyways, i think it's pretty sad and embarrassing that Microsoft is having problems with supply issues during the 3rd year in the market. I fail to see why they even limited their production if they spent all that money on 360 advertisements and Halo3 marketing during the holidays, they should have been pumping 360s out of factories non stop at that point. Maybe MS has better quality control now and changed their manufacturing process for more stable 360s?

Shortages the 360 comes in 2 or 3 models ? so they have to get the ratio of production for them correct ,also model changes from 95 to 65um and so on result in production line changes Before changing chips they probably overproduce for a while.As It takes time to ramp up production of the new version and do quality testing and so on resulting in shortages of whatever model they did not produce enough of prior to the MFR changes so it's not supprising to get supply shortages of one model or another for short periods.

 If this is the reason, MS is in a lot of trouble. Replacing a component on the fly is what good consumer electronics companies do. If you have a Mac Book, 6 months later there is a good chance that half a dozen components in the new one are different then the one you have. If a part comes out that's 1 dollar cheaper, and you sell millions of your devices a year, having the ability to change to that part quickly and cheaply equates to millions in profit. Same if a part comes out at the same price, yet is more reliable (or produces less heat). These parts add reliability, thus improve profits. Asus does it all the time. Apple does it all the time, intel (a huge manufacturer of motherboards) does it all the time, and Sony does it all the time. I bet what's in a PS2 today is not exactly the same thing that was in a PS2 6 months ago.

Anyway, MS needs to learn how to do something like this without batting an eye, or they have no chance of winning. 

.

After dealing with Chinese production lines, the Chinese New Year, and other factors in my last job, it's a simple answer:

Very hard. 

Stop making the haters deal with reality, it makes their heads pop!