Jon writes:

...

Two other possibilities: (1) It's merely an independently produced cryptosystem disguised as a "leak" to save its creator the trouble of asking experts to analyze it for him/her.

It strikes me as rather foolish to mail off anonymous copies to several individual recipients (Matt, Perry, Tim, ...) in addition to the list, if S1 is a real leak. Why aid the traffic analysts by firing off multiple messages through the remailers ?

A third possibility comes to mind, that person or persons associated with the list are using the post to focus on cryptographic efforts in lieu of political or apocalyptic diatribes.