It doesn't surprise me that the white iPhone 3GS is apparently selling out everywhere, for several reasons.
• Apple's likely making far fewer of them than the way more popular black iPhone.
• Notice that's the cheaper 16GB model that's completely sold out here—there are still 32GB models, for obvious reasons (price).
• When I found out I'd have to enslave several small children to AT&T to "upgrade" to a 3GS, I was planning on going white to have something different from my old iPhone 3G, which is black. (Okay, and maybe to have something a little different from most other people.) My guess is that it's not an uncommon instinct, and that many people buying the white iPhone 3GS already had an iPhone 3G, or are consciously trying to stand out, as flawed, yes, as that notion may be.