Incidentally, 2.2 (via the CM6 test) runs just fine on my Sapphire. The joy of Free Software is that I can fix my own device that is no longer the flavor of the month. T-Mobile will never give that device an Android > 2.0. But the community can, and it works much better than the stock image.
(Android 2.2 sort of works on my EVO 4G. The 4G doesn't work, but then again, since the EVO came out, Sprint's 4G hasn't worked in Chicago anyway. So I guess 2.2 works fine on the EVO, actually.)
Anyway, it all comes down to how you define supported. If you mean, "in the form of a bloatware ROM filled with ads for your carrier", you're right, Android 2.2 is not supported by anything. If you mean, "I can check it out from git, compile it, and load it onto my phone", well, pretty much everything supports 2.2 now. Pretty awesome, if you ask me.