[a3n]

Yes, but that would be worthless without the next step of targeting an individual identified by the dragnet. I imagine all you need to be a person of interest is to have communicated with someone who is a small number of hops away from some other person of interest. Or later, when they really get going on their data mining, all you'll need to have done is to have said something particularly interesting and negative about the NSA or the government; they'll have to start doing that, because they'll run out of actual terrorists and they'll have to find a way to keep racking up "successes."