Has a Prog album ever won a Grammy?

Yes never got a nomination in their heyday (although later songs like "Blower of a Wicked Fart" and albums like Big Generator were nominated), Genesis was never even nominated until they started playing Broadway show tunes and romantic movie melodies, and Tull was nominated once for Heavy Metal, of all things, but never for any album from the 1970s.

No, the grammies are a joke anyway, it's the mainstream music industry patting themselves on the back, feeling self-important. 

Just look at the case of Jethro Tull winning in 1989, for an album released in 1987, for the heavy metal category. So there goes any credibility thrown out the window. 

Similarly, there's a Ukrainian rock band Okean Elzy aka OE (Ocean Of Elza, that is). Like ten or so years ago they won some Ukrainian music award in the category of best pop band, which their leader commented with an evident taken offence. 

I remember of the Oscar for best foreign movie that came to the Soviet "Moscow Does Not Believe In Tears" in times of tension over Afghanistan in the 1980s. Not that I protest against - but I'd say, there were no less than 50 Soviet movies that undeservedly never got such a recognition. There was for example a great Soviet comedy about a naive kind-hearted retired private soldier that travels all over the country in search of an ideal wife. That comedy was absolutely Italian in its spirit and was not that far from Fellini's style. But the Oscar was given as a sort of political gesture in the early 1980s...