And how hard would it be to turn this inward. In the New York Times:
A consortium of major universities, using Homeland Security Department money, is developing software that would let the government monitor negative opinions of the United States or its leaders in newspapers and other publications overseas.
Such a “sentiment analysis” is intended to identify potential threats to the nation, security officials said…
American officials have long relied on newspapers and other news sources to track events and opinions here and abroad, a goal that has included the routine translation of articles from many foreign publications and news services.
The new software would allow much more rapid and comprehensive monitoring of the global news media, as the Homeland Security Department and, perhaps, intelligence agencies look “to identify common patterns from numerous sources of information which might be indicative of potential threats to the nation,” a statement by the department said…
Even the basic research has raised concern among journalism advocates and privacy groups, as well as representatives of the foreign news media.
“It is just creepy and Orwellian,” said Lucy Dalglish, a lawyer and former editor who is executive director of the Reporters Committee for Freedom of the Press.