It's a beautiful dream: buy whatever phone you want and then use it with whatever service you want. And it looks like that's a dream that will come true in Japan.
The Japanese government has launched a review of the SIM lock system that doesn't allow people to simply swap their SIM cards out to talk on different carriers, something all three major Japanese carriers prohibit. It's especially annoying to Japanese travelers who want to travel overseas with their standard phone; swapping in a SIM from an American carrier, for example, won't work.
Don't get excited for this sort of thing to happen here, however. In the US, you're able to swap SIMs if two phones operate on the same type of network, but AT&T and Verizon run different types of network that aren't compatible. That's why you can't get an iPhone on Verizon no matter how much hacking you do to it. [Yahoo News]