You have to register for HOTS to keep skiing after 10pm. Not only do you have to register, you have to go and get your pass rescanned so that it is modified to work after dark.
As Billy said, get there early, register early, and get all checked out and good to go ASAP - the office last year closed at 2 or something and it was impossible for some of us to get our passes to work on the RFID things, needed to get a host to let us through and explain to every liftie what was up. Hopefully its been changed so that its easier, but I doubt it.
Thomas and David, you guys are filling blank spots on the team, but we should have room right now for one more if you want to ski (we have 14 I think, limit is 15 a team). If you want to come ski tomorrow, shoot me a PM, I'll try to get a hold of Thomas and David and get them to give the registration office a call and remove themselves from the team.