Apparently, yes. If you allow for skiing on grass (the ground covering kind, that is) as well as snow (and ice, slush, rocks, etc).
Check out this impressive bit of summer skiing on the grassy slopes of Mad River Glen, that was posted by skier Dave Bouchard, and shared by the folks at Adventure Skier, featuring Bouchard on his Marquette Backcountry Skis (see "Are Marquette Backcountry Skis the Solution for Undependable Winter Weather?" Free Sport, 11/08/12), his daughter (who seems to be having at least as much fun with the video camera as he is with the skis) and their dog (also having a pretty good time).
I picked up a pair of Marquettes last season, and to answer my question about the effectiveness of Marquettes in less-than-ideal snow, the answer seems a definitive yes. (My last run of the winter was over a little bit of snow, too much dirt, and too many tree roots somewhere in the Holyoke Range. Considering the conditions, they worked like a charm.)
After watching this video, I may have to dust off my Marquettes, find myself a steep, grassy slope somewhere, and start my season before the snow starts to fall. Of course, if there's a freak early season storm, that would be okay, too.
So here's to a great final weekend this summer, and a cold, snowy winter ahead.