A chance encounter in the canteen:
"Oh, hey Bob! You don't know who I am, hi, I'm Steve McDougal here, from the OPHELIA project. Don't take this the wrong way but I've been reading your diary and I can't help but tell you that I feel the EXACT same way about our organization's spying on ordinary Americans as you do."
"Are you kidding, Steve! I know exactly who you are - I've been reading your diary for months, too!! The one you keep in : C:\Users\Steve\Documents\steves private thoughts.doc? You were writing in there just this morning about how even in Orwell's 1984 he could at least turn away from the monitoring TV!!"
"Oh wow Bob. Or that entry you wrote the other day about Quis custodiet ipsos custodes - I think this was where you were writing about your wife Sue getting banged by the FedEx guy"
"Yeah well ha-ha Steve, I could tell you never bothered to look at your wife's work Blackberry number!"
"What? You're kidding!"
"No, check it out. You got something to note this down with, I know it by heart: it's 505-234-9918. Didn't you ever hear Sue and I reading excerpts? That is some hot stuff."
"What - no, I only listen to you guys when you're actually fucking, and that hasn't happened for months. If you want to really hear something, try your home around 2 PM tomorrow, since your wife ordered something from Amazon again."
"Yep :). But so anyway, what were we talking about again?"
"Oh the diary stuff. Yeah your thoughts are like a mirror image of mine."
"Yeah I don't know how we never met before, I've been reading your diary ever since you filed a complaint about the lunchmeat. But what did you think about my thoughts on Director Alexander?"
"Well to be perfectly honest with you I think you should have kept them to yourself."
Also, it means that different people are telling themselves, "I'm making a better search tool!", "I'm making a better scraper!", "I'm making a better optical tap!", without putting it all together (https://www.youtube.com/watch?v=HoT-h0S1gkE).
One of the facets of the banality of evil lies in people's inability or unwillingness to integrate in their minds the purpose of their day to day production as it relates to the larger picture. In an intelligence agency, the larger picture is obscured by design.
What is that supposed to mean?
(disclaimer: I am not very knowledgeable about electricity/electronics, so forgive me if I'm a bit hand-wavy or wrong about the details)
The actual electricity output from a wall-socket fluctuates continuously by a tiny bit over time. I suppose this goes for both the exact magnitude of power output (is that voltage or amperes?) and the exact frequency being ever-so-slightly above or below the expected 50Hz. These fluctuations can be measured (or fingerprinted) by carefully measuring the output of electrical appliances, such as the crackles and pops in audio recordings or brightness of light bulbs, and in fact many other things.
The other important fact in this trick is that apparently these fluctuations are all the same over the entire grid (or subsections of it, I guess, depending on network layout). They are also pretty much random. This means that if you keep a log of these fluctuations over time, you can timestamp recordings of pretty much anything with extreme accuracy, by matching up the patterns of crackles or power fluctuations in the recordings to your logs.
This would then allow one to detect fake call logs, video/audio cuts and splices, stuff like that.
It's not a gigantic privacy risk (therefore probably not what the GP was thinking of), at least not from the applications I can think of the top of my head. I do love side-channel attacks like these, though. They're always so clever and out-of-the-box :)
The NSA is full of intelligent people. Keith Alexander went to West Point. Indeed, one of the reasons he became DNI was his extensive education in telecommunications technologies/signals intelligence (he has a number of post-graduate degrees in that area).