...do it today. Registration is capped at 8400 skiers for the 2011 Birkie and the Kortelopet. They are near that limit and announced today that registration will close at 6:00 p.m. tomorrow (12/18).
This is very early for the race to close. Last year, I think registrtaion was open until late January/early February.
It's a great race on a challenging course.