I see two likely options:
1. Trust 'em or bust 'em: Train thoroughly, monitor closely, punish those who violate opsec.
2. Flip the comm switch "off".
I propose option one. But I'm biased.
As I said, I think there is a legitimate OPSEC concern. I think CBFTW's commander had the right idea. Let them blog, but review the blogs before posting.
From an MI/PSYOP perspective there is much there that can be used by an astute observer on the enemy side (I include NPR in that description), and used to good effect if it is allowed to become overly critical of the mission and chain-of-command (a little can be seen as healthy).
I like reading them. But unlike most civilians, you and I read them through a different mental filter. We know the culture. We know the dark humor GI's use to keep up their own morale. We're familiar with the complaints of military life, and the reasons for them, and why they will always be.
A vet reading these blogs takes away something different than most civilians. And therein lies the concern IMHO. We're I a commander there, I would insist on reading anything posted publicly by my soldiers before it goes out. First to make sure that nothing innaccurate or damaging goes out, and second, to guage my own troop morale. And I'd be sure they know that it is for their own safety, because the war they're fighting is behind them on the homefront as well as in their forward sector of fire.