The Infoviz toolkit is used at Project Seven by a friend of mine et al. They're working on an intelligence analysis tool which supports reinjection of explicit knowledge earlier in the categorisation/discovery chain to guide discovery.
This is a different approach to the one I took in my signature based approach in my paper "Community-of-interest predicated program trading" where I suggested using centroid categorisation augmented with off-center categories. The Project Seven techinque relies on heuristically directed iteration (or as it's known in lay terms - trial and error) where my technique relies on the visualisation of the categorisation centroid. I think both approaches have merit and would produce good results.