Supposedly Carnivore only targets specific kinds of traffic and doesn't really monitor everything at once. It's not like (again, supposedly) Echelon that examines everything and then red flags certain items. Carnivore is only looking for certain things. Also, there is no outside access to it. Someone has to physically come in and remove the mass media (what ever that may be: more than likely a hard drive).
Afraid I'd have to say that in this instance your conclutsions are inaccurate. For more information, see the FBI's Carnicore site at http://www.fbi.gov/hq/lab/carnivore/carnivore2.htm
Let's see, I want to send email to someone but I want it to be completely anonymous. I go to safeweb.com or any other anonomizer and get myself a hotmail address. I then send it to the recipient with PGP encoded text. He logs on to hotmail through anonomizer and retrieves it, decodes it and reads it. If I was really smart I'd bounce around a couple of other proxies while I was at it.
Again, check out the above link. Your idea of going to an anonmizer would be useless as Carnivore scans the traffic directly from your ISP.....before it ever gets to the anonmizer. Granted, encrypting your message before ever logging onto your ISP and then sending it via it's encrypted format would prevent it from being read in cleartext but considering what Congress is proposing, the sending of encrypted messages could be just what the FBI would need to start looking deeper into your life.
Carnivore? Toothless!
No breach or attempted breach of one's civil liberties is toothless....especially the right to privacy.