Looks like you will personally receive any gift cards which you did not share. I have been receiving emails with the following:
"Dear ___________,
Our records indicate that due to technical difficulties you were unable
to share 3 of the $2 Dunkin' Donuts gift card(s) you received in
The American Express Gift Chain with your Facebook friend(s) before
the February 29, 2012 deadline.
We will be mailing the gift card(s) directly to you within the next
three weeks, so that you can forward them on to your friend(s).
We sincerely apologize for this inconvenience. Thank you for being a
part of the American Express Gift Chain.
Sincerely,
American Express Customer Care"