For in-depth coverage of the new "Like" campaign Facebook has launched, check this:
Protect Your Privacy Opt Out of Facebook’s New Instant Personalization – Yes You Have to Opt Out
A wonderful blog post that I would have to recreate here if I had not seen it. Instead, I will summarize:
Facebook is trying to connect its users to all kinds of websites.
Every Facebook user is automatically signed up to "partner" with these sites.
To opt out, you must change a privacy setting AND you must block certain applications through Facebook.
From the above blog post:
So to recap to completely opt out you need to
1) Go to your to your privacy settings ->Applications and Websites and uncheck box at the bottom. (Here's the link: http://www.facebook.com/settings/?tab=privacy§ion=applications)
2) Then click on the links to Yelp, Pandora and MicrosoftDocs.om on Facebook and click on “Block Application” (Here's the link to these pages: http://www.facebook.com/help/?faq=17105)