Thanks for the link! This clears things up considerably.
To me this would be the "John Walker Lindh" amendment; they're extending the existing law revoking citizenship by serving in a hostile foreign (state) army to serving in a hostile terrorist organization. Once citizenship has been revoked (by Congress? before a judge? by decree of the president?) then expatriation proceedings can begin.
This, thankfully, isn't as bad as it's made out to be. It's just removing the loophole that you can be in a terrorist organization actively hostile to the United States and expect to be treated "nicely" simply because you're a US citizen. If you join the Iraqi army, you're stripped of your citizenship; if you join al-Qaeda, you're not.
However, this brings up an interesting paradox. If we intend to level the playing field between terrorist organizations and state armies by declaring American members of both equal (i.e. non-citizens), does this not implicity bind the US to treat non-American members of terrorist organizations and state armies equally as well? In other words, does this not mean that, since the US is leveling the playing field between Americans in the Taliban and Americans in the Iraqi army, that by extension since non-American Iraqi prisoners are considered POW, the non-American Taliban prisoners must be as well?
Unless, of course, the provision is made with only citizenship in mind; that is, we strip an American Taliban of his citizenship so we can lump him in with the rest of the non-combatants, since we automatically strip American soldiers in the Iraqi army of their citizenship and lump them in with the rest of the Iraqi army. Consistent, but I am yet unconvinced either way.
And what if it's a domestic terror organization, like militias? It makes sense we strip Johnny Lindh of his American citizenship and (implicitly) assign him as an Afghani citizen. But what of a gun-nut born in America, raised in America, and has never been out of the country? Or is he (and John Walker Lindh) considered stateless? In that case, does that leave open the possibility for a state diplomatically hostile to the US, say, France, to claim him as a resident and thus force the US to respect Franco-American agreements? (Assuming, of course, the stateless person in question accepts French citizenship)
-- Alvin