I've always been curious about this myself, though is it even technically possible for something at such a low layer to be aware of what is happening at a higher layer?
Ex: if I'm writing a letter in MS Word to mail to my buddies in Jihad land the cpu does not really know that I'm writing a letter or even care about the program I'm using, it's just following low level assembly instructions send by the various layers of software and hardware as I'm typing the letter. I suppose it could take all those actions and store them somewhere to be sent to the NSA and the reverse engineered, but that on it's own would be quite the feat, as I don't think the cpu would even be able to use the network card without drivers, unless there's built in drivers into the cpu for all the popular network cards. That would also generate traffic that someone would eventually figure out while messing around with a packet sniffer on their network.
Of course it could also be producing some supersonic sound waves that can be physically picked up by proximity.
Overall, I don't think it's feasible, but I'm curious myself if perhaps, it is?
I know they do intercept Cisco routers and put special chips in them to basically act as a back door, so if they could do the same to cpus it would be a gold mine for them. Of course that's also much harder from a technical stand point just because of how small a cpu actually is. It's pretty hard to modify a semiconductor die.
Oh I am quite sure it is possible and is happening .. Its fun to make fun of, but while 'tounge in cheek' it is with a certain level of seriousness to it.
Can we be sure as in 100%? Hell no, nothing in this verse is 100% except perhaps the love for our children.
To take your jihadist word letter as example, here is my personal take on it.
Lets start under water.
http://tech.slashdot.org/story/08/12/19/1932219/mediterranean-undersea-cables-cut-again
http://www.theguardian.com/technology/2013/mar/28/egypt-undersea-cable-arrests
One way or the other, your traffic is being monitored and analyzed, analyzed by relatively simple constructs, wordlists, encryption schemes etc. but also more advanced stuff, AI, basysian reasoning, neural networks and more.
So your traffic got flagged. U might think proxying or even chain proxying your traffic is smart but based on relativly simple statistics tools you are easily identified.
Now they know where you live. A couple of options here
1. Break in, install malware/cameras while you're not here
2. Use non-invasive surveillance methods, while not as accurate as numer 1. they are still pretty accurate.
3. The mobile cell tower: The dark van parked outside your house, fires the emp that fires up the hidden 3G modem in your intel cpu and taps into everything from there. (PC not powered on? We issue a WOL on the bus and take it from there)
Now, the NEXT jihad letter you get around to... We're watching you.. errh freudian slip, THEY are watching you...