Plenty of people are tracking the chans; 8chan's /k/ occasionally had a thread about feds using screenshots from various chans. I'd bet my shoes that a great deal of Open Source Intelligence types float around on /k/ and other politically oriented boards as a way of scoping up occasional gold nuggets and taking the temperature of things.

Someone is watching, but it's like panning gold from a river, except the gold is "Actionable Intelligence" and the river is high-pressure sewer main -- lots and lots of shit but little actual gold. High effort, but little yield.