Professor Stephen Hawking and Arnold Schwarzenegger drop in for townhall Q&A with Zuckerberg
Facebook account of American airlines hacked and defaced with 'objectionable and offensive' content
The Twitter account belonging to the CFO of the microblogging website falls victim to hack
Social networking giant responds to user complaints about hoaxes and spam in newsfeeds
Facebook is secretly working on a version of its site with stricter privacy controls and office collaboration features