The Free Shipping Day offers are for U.S. orders only and the delivery promise is for in-stock merchandise.
It appears that nearly half of the merchants listed offer free shipping on all orders, while the other half have restrictions on the free shipping offers - such as minimum purchase amounts, etc. Some of the merchants require you to enter a promo code in order to get the free shipping, so look at each offer to see if a code is given on the freeshipping.com website.
Amazon.com has posted their Christmas Ordering Cutoffs Calendar, with Thursday, December 17, 2009 listed as the last day to get Free Super Saver Shipping on qualified orders with delivery by Christmas.
photo: ricohman, sxc.hu