The cracking open of Facebook's privacy settings to much more access from outside the site has led to some serious anger and disappointment from Facebook's users. On May 31st, a large scale demonstration of this anger will take place. Users will deactivate their accounts, leaving Facebook for maybe only one day, but many may stay off permanently.
We shall see what happens from June 1st on.
Mashable has more info here
To see an example of what Facebooks changes to their privacy settings has unleashed, go to the FacebookSearch Search Engine. You can search through chat conversations for the sites users by any word contained in any chat.