To be fair, we should have expected this: Back in June, there were reports that HTC representatives had been talking about a "With Google" licensing issue, which disallowed them from loading phones with propritary modifications to Google's OS. Sense is all HTC, and the MyTouch 3G is slapped with a Google logo, so this forthcoming update, which was announced at a press conference in Taiwan and will be available from HTC's website at some point in the near future, sounds like a distinctly foreign interest. So, balls.
It's worth holding out for possible "clarifications" on this one—please, HTC, Google, or both, say it ain't so!—but this hemisphere's outlook isn't so great. There's nothing like a massive, terrible caveat to piss all over some otherwise wonderful news. At least we've got our homebrew.
AU: If I were a betting man, I'd place my money on the Three version of the Magic to be able to load Sense, but not the Vodafone version. The Vodafone version has the Google Logo on it...