From the Nintendo Tech Support forums:
"According to member TACOSLOVEME, who just talked to a NOA representative (or so s/he says) it will be out at 6:40 Pacific/9:40 Eastern."
Well, it's past 8:40 CST here, so I guess people should start receiving notifications now. Hm, strangely enough, when it passed 8:40, the tech support forums just suffered from a system error that didn't go away for a while.
[UPDATE] The tech forums are back up, and from what I've read, we may not get the update right now due to server flooding. Makes sense to me.