499 days in advance is correct for room-only reservations. If you want to book a package, you must wait until the rates are released for that year, which usually occurs in early-August for the following calendar year.
So for example, if you want to book a package for January 2012 (which is less than 6 months from now), you can't do it yet. You have to wait until the 2012 rates are released, which will probably be in about 1-2 weeks or so.
You can book a room-only reservation up to 499 days from now, but you won't be quoted a price (unless you're booking for a stay within 2011). Room-only reservations require a deposit of one night's room rate + tax. Since the rates aren't out past the end of 2011, your deposit will be based on the very highest price for 2011. Any overage you pay as a result of that inflated deposit will just be applied towards your balance due.