Nintendo sold almost a million Nintendo DS systems in the U.S. during the month of November alone. If they can keep the stores stocked, they'll be able to hit that or more in December. It now appears that's could be a fairly significant "if".
I tend to think not fabricated. Between Wii production and trying to keep a million systems in the U.S. this month, I'd guess they just don't have resources to throw at the problem. Just a guess.
I bought two DSes in the past month (one for myself and one as a gift).
Searching online was pointless, no one had them in stock that I could find, aside from ebay/amazon marketplace vultures.
However, I easily found white DSes at the local target, and a few seconds on gamestop.com allowed me to find pink DSes in stock at a store within 10 miles (fourth closest store, in Saugus).
Based on my discussion with the guy at the GS, they're selling like hotcakes. He had a full stock of units when I came in, but they had just been restocked the prior day.
So, moral of the story: they're obtainable without too much trouble, as long as you don't mind combining online with local. Let your fingers do the walking.