Print the first page of the panic report, and the support page linked above, and bring them with you.
Note that the recall only applies within three years of purchase. After that, Apple may refuse the service. In that case, you may be quoted a price of about $300 (in the U.S.) for a "depot repair," which involves shipping the unit to a central repair facility and takes about two weeks. For that flat fee, anything found wrong with it should be fixed, not just the logic board.
The model was discontinued in February 2011, so the replacement program will be ending soon. Some units may have been sold by Apple as refurbished after that date.
Back up all data on the internal drive(s) before you hand over your computer to anyone. If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.
Sometimes the replacement part is also defective, so be prepared for that possibility.
If it's too late for your unit to be repaired under the program, and you don't want to pay for a new logic board, you may be able to stop the panics by disabling automatic graphics switching.