Doing it in the very same slam? I can't think of any recent example. Still think what Bjorkman and Melzer did are very impressive considering RG and Wimbledon are so close in the calendar and it shows you can go for both singles and doubles in the same season if you got the talent for it.
As I said, last time was Kafelnikov @ RG '96. Last times in other slams (unless I'm mistaken) have been Edberg @ AO '87, Stich @ Wim '91, and McEnroe @ USO '81. (did that also in USO '79 and Wim '81, '83, and '84)
Anyway, I think doubles would be better if top 10 played doubles more often. They don't do it in slams because they concentrate on singles, but the two-week format of Indian Wells allows them to play doubles there. Of course Miami has the same format, top 10 don't usually play doubles there. And look at the recent IW and Miami finalists, doubles specialists haven't celebrated in IW as often as in Miami. Actually, because slam doubles don't have the best possible field, I think winning Olympic doubles (or maybe even IW doubles) is more difficult than winning slam doubles, Olympics definitely have the best field in doubles.