The basic offer is a seven-night package for the price of a four-night package. The package includes your room and Ultimate Park Hopper passes (7 nts/8 days) for everyone in your party. Disney will not allow you to drop nights from the passes and everyone booked in your party must take the passes.
If you are going more than four nights and plan to spend all your time on Disney property (theme parks, water parks, Pleasure Island, DisneyQuest), this is an EXCELLENT deal. It is especially good if you spend seven nights, as you are getting three free.
The package won't be great for everyone. Not everyone plans to stay on Disney property the entire time and not everyone ventures away from the theme parks. Hopefully there will be room-only offers as some point for those people not able to take advantage of this package.
For those trying to figure out what adding children does to the package price: All that is added is the price of their pass. Each child (3-9) adds $212.00 to the package price and each junior (10-17) adds $266.00 to the price. Remember that the prices being mentioned here are for Disney Club members. The package prices have not yet been released for the general public. As I understand it, Disney Club members are being offered $50 off the total package price. If you want to get an idea what your cost might be, visit Disney's website and use the package booking engine to price a four night Dream Maker package around your travel time. This will give you an idea of what a package would cost for a stay between four and seven nights.
Good luck everyone!