I somehow doubt the NSA would be the ones building it. It would probably be farmed out by the govt like the ACA website.
I agree it would be terrible if the govt ran it, but would make sense is for the govt to actually plan it and put regulations around it. Provide a framework for private companies to work off of.
That's why I said lending their talents. The NSA and FBI would definitely consult on something that big.
Actually they'd do it regardless of whether it was built by the public or private sector.
I'm in the DC area – so I know exactly how bloated and utterly incompetent most defense contractors are (I worked for a couple). So I have nearly zero faith in them doing a better job.