I didn't read anything about an NDA for this beta?
I'm not aware of one myself, but Stardock does seem to have restricted access to a lot of the threads about the Mercenaries beta; at any rate, I get an 'access denied' message if I'm not logged in, which is a change from earlier in the week.
Wait, we're not meant to tell non-Founders anything about the expansion?
Apparently, yeah, we're not supposed to talk about it, or at least not much:
Phew. Sigh of relief that people like the expansion. Remember that this shouldn't be discussed yet generally since only Founders and reviewers have access to this.
Post #113 in the FOUNDERS: Mercenaries BETA thread.
Not sure that they have any legally-binding stuff mandating that we not talk about the Mercenaries beta, but it's clear that at least Frogboy doesn't really want us talking too much.