"Facebook is entering into business deals where the Facebook part of the transaction is user information and the other party's part is unknown," Opsahl said.
Even if partners didn't pay, Facebook is leveraging its access to user information to construct business deals, the attorney argued.
Facebook made it clear that friend information in windows at websites is for users' eyes only.
"It really has no privacy implications," Zuckerberg said at f8. "I think this means people will be sharing less information when they don't need to around the Web."
Facebook users have to be signed into the service for plug-ins to trigger and sharing requires people to click on icons.
Privacy advocates worry that outside websites could get Facebook information considered public, with gradual changes at the social network forcing more user data into that category.
via physorg.com