A PIN offer is an offer you receive from Disney, either by post card, or email, giving you a discount. It includes a "PIN" number that identifies you, and can only be used by the person that Disney sends it to. Apparently, Disney has been sending out some PIN offers for the
free dining promotion recently.
Right now, the only way to get the Free Dining is with a PIN offer, it is not available any other way at the moment.
However, for the past few years, Disney has made the Free Dining offer available to everyone. The offer is usually announced sometime around the beginning of April, and is available for people traveling from around the end of August to perhaps the beginning of October.
We don't know for sure that Disney will make free dining available again this year, but we are hoping that they will, and talking about it here.
If / when it is made available, it usually is announced to, and available to Disney Visa card holders first. Then, a few days after it becomes available to the Disney Visa card holders, it is released to the general public. Obviously, if you have the Disney Visa card you will get the best chance at getting the room / resort you want on the package, but if you call as soon as it is opened up to the general public, you should still have a pretty good chance at getting what you want.
The only thing to do for now is wait, and keep checking back here for updates / news. It's a pretty good bet that the news will hit the boards here before you hear anything from Disney.