It's still not a hugely popular trick, but a few edits from this year have had them. Collin Collins threw one 3 or 4 years ago when they were unheard of and somehow it wasn't a huge deal on this site. I also see kids throwing them from time to time when I ski Whistler.
Andy MahreCASABON (best in my opinion)HenrikDelormeABMKarl Fost
there's more, those are just off the top of my head. So YES, it's been done quite a lot
Andy's may have been first ever done if you're talking about the one from idea at pc on the hell bents! Inspirational someone should find that shot and post it!
i did one last week while trying switch butter 3's. at the last second i decided i'd go for switch 3 instead but still opened up my shoulders. it was on like a 10ft jump too so it was pretty sketch, i'll try them again today and get a vid for you guys.