Facebook's Instant personalisation tool was launched back in April last year... but it is only gradually being rolled out now.
So what is it? Should you be worried about it? And how do you disable it?
Instant Personalisation is like Facebook Connect in that it lets another site use information from your Facebook profile. But you don't have to sign in to it. Facebook does it automatically for you. If you have Facebook open and then visit one of these other sites you'll a notification the first time that "personalisation" is going on. If you don't disable it, it will run and personalise that website to you.
Okay, it's not giving out your info to every site - just a limited list of them: Bing, film site Rotten Tomatoes, TripAdvisor, TV site Clicker, Pandora, Yelp and a couple of others.
It's not your whole profile either. These sites won't know what school you went to or what your latest status update is provided you have set these to private. They can only access public information like who your friends are and what your name is.
Understandably though, a lot of users aren't happy about this sharing and get a bit freaked by sites knowing their names (it pops up with a personalised greeting at the top "Hi Anna" or whatever.. and they just want to look at film reviews (say) without perky information about what their friends do, which is, after all, on Facebook.
If you don't like it.. just switch it off. It's possible, though not exactly as straightforward as it might be...
[nb - you can only switch it off once it's been enabled, so unfortunately you have to wait till it starts]
>> FACEBOOK PRIVACY ALERT: As of today, NEW PRIVACY setting called "Instant Personalization" that shares data with non-Facebook websites is automatically set to "Enable." Go to Account >Privacy Settings > Apps and Websites >Instant Personalization > Edit Settings, and un-check "Enable". If your friends don't do this, they will be sharing information about you.
Information about instant personalisation on Facebook.com
UPDATED: 7JAN 10