kokoko1 submits this snippet from The Telegraph, which reports that Facebook isn't alone — now YouTube, too, is being censored in Pakistan. "The blocking of YouTube comes a day after a Pakistani court blocked Facebook amid a growing row over a competition on the social networking website to design cartoons of the Prophet Muhammad." Update: 05/20 18:58 GMT by T : According to an anonymous reader, Wikipedia and Flickr are out, too.
Update: 05/21 12:11 GMT by KD : And now add Twitter to the blocked list. This post claims that more than 1,000 sites are being blocked in Pakistan.