Does Micro SIM Lock the "Unlocked" iPad into AT&T?

So still trying to sort out all the news about Apple's new iPad and whether it was a vote of confidence (or surrender) to AT&T. Looks like more of a mixed bag, but I need more information. Here's one piece of the puzzle. An explanation of the new SIM card. (It's getting a lot of traffic, so you might have to hit the link a few times)

Apple iPad's Micro SIM Explained

The post says: "In fact, from AT&T’s perspective, this is better than a software lock in some ways — you’re not going to be able to download a hack that gets you on another network, so you’re totally at the mercy of your carrier at choice for providing a compatible card."

Hmm… but how difficult really will it be for other carriers to come out with micro SIMs? Can't be that hard. And they have several months to get up to speed. I don't think the jury is out on this yet.