The main activity of senior FBI and spooks alike has always been extortion. What exactly is done with it varies. For FBI, it may include coercing aid to recruit into "terrorist cells" that may then be prosecuted, or coercing false testimony, i.e. perjury, in criminal cases. Among spooks, coercion is used to operate networks of "assets" for information gathering or covert action, often for official purposes, but not at all necessarily so. "Classified" offers a big tent.<p>So, Twitter's interest in FBI and spooks will be to leverage their skills operating on information Twitter has unique access to. This could be a much more lucrative business than advertising. Of course this makes Twitter useful directly to the spook agencies for their own purposes, another revenue source.