Kind of scary how they asked for all PM's mentioning BFL. I recall a while ago theymos discussed the idea of adding javascript PM encryption as a way to protect the forum from unreasonable searches and seizures. It isn't the best way to do it, as of course theymos could modify the javascript at anytime (he could even potentially be compelled to do so by law), but modifying the javascript is detectable, and messages that were sent and viewed with the unmodified javascript are still safe. It adds an extra layer of security, which should be sufficient for most PM's. It would also be very useful should BitcoinTalk's database ever get compromised... again. Anyone who has something really secret to tell should use something like PGP instead of this however.
I think we should consider adding this to the new forum software.
I think we should consider adding this to the new forum software.
The other big problem with that is how to handle private keys. If the private key is generated from your password, for example, then forgetting your password would mean losing all of your PMs. Most people aren't prepared for this.
This is pretty much the whole forum, right? 
It was 2.3% of topics. (This still amounted to ~5 GB of text.)