As our friends at Sophos explain, offers purporting to be from Tim Hortons started targeting Canadian users Monday. Users were asked to "Like" a page and share it with Facebook friends in exchange for free coffee.
Today, the scam has spread to include Starbucks. Tim Horton's is primarily a Canadian chain and the ubiquity of Starbucks makes U.S. users potential targets.
We've seen this sort of scam before -- either with the promise of free goods or access to Justin Bieber's cell phone number. In some cases, users are tricked into a "likejacking" cycle after accessing a nefarious link. In others, users agree to install a rogue Facebook application.
In this case, users are asked to provide an email address and other sensitive information.
The danger with these sorts of scams is that they can spread so quickly across social networks. Unlike email chain letter scams of the past, these scams can post to your Facebook page and instantly entice others into falling for the same rouse.
Do not give your email address to these rogue companies. Do not "Like" their pages or share the scam with your friends.