The band is using Culture Jam's custom Twitter application to manage the Twitter whuffie track exchange, so retrieving your free copy of the live recording is a simple-three step automated process.
Click the "Connect to Twitter" button on the application landing page, grant the application access to your Twitter account and tweet as instructed. You can then redeem your music download using the provided iTunes gift code and the I-scratch-your-back-you-scratch-mine deal is complete. Should you also want to take home one of 15 White Vinyl LP editions of the Backspacer album, you can enter to win that as well.
Pearl Jam's Twitter giveaway is by no means unique, but it does signify that giving away free tracks via the microblogging site is a trend that here's to stay. Obviously more and more artists are realizing the power of a message spread through Twitter's real-time digital airways.