Per this post on the SO/SE blog (which, curiously, does not include math.SE in its graphic list), it looks like the admins will choose moderators pro tempore at about 7 days into the public beta. In the roughly 24 hours that we've been in public beta, I've wondered several times: should we push to have the admins choose moderators pro tempore sooner (e.g. now)?
edit: to try to get a bit more clarity in response to this question, I've created CW answers "YES" and "NO" below--please up/down vote those as you see fit.
edit2: see also: elect our (Provisional) Moderators