Thanks to the Consumerist, there is now available the complete list of companies that have signed on with Facebook's Beacon program (allowing people on facebook to see what you've bought and from where):
CBS Interactive (CBSSports.com & Dotspotter)
National Basketball Association
Sony Online Entertainment LLC
And now, thanks to Wikihow, there is a whole set of directions on how to BLOCK FACEBOOK BEACON entirely, but only for Firefox users. I skimmed it quickly, and it doesn't look that hard, so if you use Firefox, you may want to take a look.