Takes a while to get it nice & flat, and the second side HAS to line up, but I've filed a couple of 14mm axles to fit 10mm forks. Only the part that fits into the dropout, so it looks like they've got sort of a flat channel about 10mm wide.
No problems from either wheel, and no work required on the forks. It also means they don't turn when you put the nuts onto them, which is a pet gripe.