Survey of Japan relevant?
Is this a good place to throw in a bit about the Japanese situation? Though I don't use them, Docomo (the largest mobile carrier and part of NTT, what used to be the old telephone monopoly), has said that they will implement a new unlimited policy this year. The first 7 GB will be unrestricted (though still best effort and so forth), but after that they will selectively throttle you as a 'power' user. In other words, you'll still have unlimited packets, but they will become much slower.
This actually strikes me as a pretty fair policy, though if they have that much control over it, I wish they would be a bit more flexible about the usage times. In other words, as a probable power user (though I'm not sure I get up to 7 GB per month), I'd prefer to have moderate throttling just during the peak times, and since the peak usage defines their network infrastructure cost, that would seem to be a better deal for both of us...