I'm so cool (Y) I saw this about 3 years ago in an issue of mountain bike action.
I think its a cool idea, but I think the problem mark said would be too annoying, it would feel like your rimming out on everything! It doesnt look that wide either.
Also, on things like gaps, a lot of people (including me) tend to kick the bike out at an angle when landing, that rim looks like it would only really work if it was a straight hit, so we would still get punctures.