In one of his interviews[1] he mentions that after he left and TrailBlazer was abandoned the NSA took what he built in ThinThread but removed the privacy shields he had in place that would encrypt US communications.

The rest of the platform is ThinThread (which was a lot cheaper than the failed TrailBlazer project).

Also interesting that a lot of the NSA platform is open source. OpenCloud for server management and Hadoop for distributed computing.

[1] I can't recall which one, in his keynote at HOPE he does make another reference to the crypto privacy shield being removed