Last month Facebook added Beacon, a new service that tracks Facebook members activities through partner websites, ie. purchasing a product, signing up for a service, and so on. The problem is that many people did not realize that their activity was not only being tracked, but posted to their Facebook News Feed. This resulted in a gargantuan backlash over privacy issues, causing several partner companies to withdraw from the service and even prompted some users to leave Facebook.
Here’s more on the Beacon opt-out options from Read/WriteWeb.