I've been wondering when someone would point this out. Mark Steyn does it as an aside in his latest column in the Chicago Sun-Times:

Speaking of which, if there's four words I never want to hear again, it's "prescription drugs from Canada." I'm Canadian, so I know a thing or two about prescription drugs from Canada. Specifically speaking, I know they're American; the only thing Canadian about them is the label in French and English. How can politicians from both parties think that Americans can get cheaper drugs simply by outsourcing (as John Kerry would say) their distribution through a Canadian mailing address? U.S. pharmaceutical companies put up with Ottawa's price controls because it's a peripheral market. But, if you attempt to extend the price controls from the peripheral market of 30 million people to the primary market of 300 million people, all that's going to happen is that after approximately a week and a half there aren't going to be any drugs in Canada, cheap or otherwise -- just as the Clinton administration's intervention into the flu-shot market resulted in American companies getting out of the vaccine business entirely.

Well, duh. TANSTAAFL.