The main use case I’ve come across is network analysis. After awhile in Iraq, the military realized killing people planting roadside bombs was stupid and ineffective since these were low level individuals sometimes doing it just for money to feed their families. The main focus shifted to building up a picture of larger enemy networks so they could be taken down in a more holistic fashion. McCrystal built the fusion cell concept [1, 2], bringing in intelligence from multiple agencies to build target packs of people and networks for operators to take down. I’ve never used the software, but I believe a key use was to help various agencies surface connections in the troves of data to build these target packs. Later, someone from the McCrystal consulting group [3] said they had a former CIA analyst who used the software to find hidden connections between people in a company, to uncover and reward the critical individuals who get things done outside the normal organization hierarchy. So again, network analysis, but directed toward finding super star employees instead of terrorists. I’m sure the software is more general then this and has other multiple other use cases, but this is the best of my second hand knowledge and seems to go along with what others have linked to here describing a node and vertices analysis tool
[1] http://www.washingtonpost.com/wp-dyn/content/article/2008/09...
[2] http://www.dtic.mil/dtic/tr/fulltext/u2/a514114.pdf
[3] http://mcchrystalgroup.com/