Open source warfare is a larger subject but today, specifically, John Robb talks about one use case where it is likely to show up, the battle between the American Dream and the Kleptocrats. Open source warfare is something that our current band of domestic kleptocrats don't take too seriously. If they did, they would be taking pretty visible countermeasures and have been doing so for years. Simply put, they are not.
The protests in Ukraine that ended up with president Yanukovych fleeing are an example of open source warfare but because of the US' huge size and federalist structure, it's unlikely to be the variant that is dominant in here. Much more likely will be open source warfare techniques to coopt lower government nodes and area denial for higher level nodes that are too big to be taken on at the time. This is likely to show up in somewhat improbably high accident rates for agents of the states when they show up in areas that an organized resistance is trying to exclude them from. Overt killings will be rarer but not unheard of.
We're a long way from this sort of internal security picture but the key tipping point seems pretty clear. The growing belief that our elections are not sufficiently honest to win change in a peaceful manner, if it ever gains critical mass, is the point on which rebellion will start.