I think some of you are giving Best Buy a bit too much credit.
I'd been checking the multiple stores for months trying to find news about Surface Pro preorders. Far from being willing to research it for me, they were all "What's that? What? They're making another Surface? Nobody wanted the last one!"
I didn't manage to get it out of them that they *could* take preorders at the nearby store until literally yesterday. And when I expressed my worry that I wouldn't be able to get one, they're like "We'll probably get two because that's all we'll ever sell and there will never be a line to get them."
Funniest thing. There WAS a line, and only one 64 gig surface to go around. The store reps looked quite embarassed this morning to have their preconceptions so quickly flattened, and were quick to blame UPS for the shortage and say there would be more in a day or so. (Implying that they were quite capable of ordering more, but probably had to order most of them long after UPS stopped taking shipments on Friday.)
And consider this: Their website didn't even have it displayed until about a week before release.
My guess is the following happened, or something similar: There was a general feel at the retail level that the Surface wouldn't sell because the last one didn't sell like they expected to (nor did the Asuses and Acers and Samsungs...), and the individual retail stores simply didn't order many. They figured it was a niche market and would only need to order one or two every once in awhile. They didn't realize people were waiting for the one with full PC capabilities (for what it's worth, there was a Samsung that had the full-PC guts and Wacom support, but didn't have the specs I was looking for...), rather than going for the ARM-based tablets that don't have much software for them yet.
On top of this, they didn't bother putting the Surface up on their website or taking pre-orders until the last minute, and once they did, seemed unaware that they were able to take pre-orders.
I did work at Gamestop in the past, and Best Buy should know by now the only reasons stores bother with pre-orders is to get a general feel for how well something will sell so they know how much to order for each individual store. That and to guarantee a customer's business before they go somewhere else. Once they realized they *could* do pre-orders, the "oh crap" moment began, thus the several-day delay for most of us who ordered one.