33 miles

I suppose the attempt to make a 33-mile long scarf is legitimate enough, but it seems less impressive that it's being made by joining a bunch of individual scarves. Isn't that the easy way out? Get enough people to contribute, sew everything together, and there's your world record.

Instead, I prefer the idea of some kind of public art installation where knitters could pop in and work on one enormous piece. That seems truer to the spirit of the challenge.