I *hope* It's just that we can't book online yet. I've checked for a few different weeks in March, April and May and every time it's said there was no availability. I would be really upset if it's actually completely booked for those three months!
To far out. Disney does not know what deals they want to offer and they do not know if they are going to raise prices. I spoke to a CM about this and it is because they don't know what deals they are going to be giving at any given time in the future, ie. 30% off or free meal plan and so on ......
You can book 499 days out, you just have to call Disney as you can't do it online yet. Since they don't know the pricing yet for 2014 they will charge you one night at the highest rate this year and adjust your bill once the rates come out.
The 2014 rates haven't been released yet. New rates have been known to come out in August, but were released as early as June/July the last 2 years, so it's anyone's guess when they will come out. You can book room only now by calling, but you will be quoted the highest rate for 2013 for that particular resort/room type and your reservation will automatically be adjusted once the new rates are released. If you want to book a package or book online, you have to wait until the 2014 rates are released.