The notifications seem to be going out in waves, slowly. I'm not sure why. Across three folks I know (including myself) with Kickstarter accounts, the emails themselves all seem to have gone out within minutes of each other, but one of them arrived just minutes ago.
I'm guessing with the volume of emails, it got throttled along the way. You can see this in the Received: headers:
Received: from o2.e2.kickstarter.com (o2.e2.kickstarter.com. [22.214.171.124])
by xx.example.com with SMTP id xxxxxxxxxx
for < email@example.com >;
Sat, 15 Feb 2014 21:49:50 -0800 (PST)
Received: by filter-219.sjc1.sendgrid.net with SMTP id xxxxxxxxxx
Sat, 15 Feb 2014 21:18:46 +0000 (UTC)
Received: from MTEzNDg (unknown [10.42.83.122])
by localhost.localdomain (SG) with HTTP id xxxxxxxxxx
for <firstname.lastname@example.org>; Sat, 15 Feb 2014 21:18:46 +0000 (GMT)
Notice that the earlier time stamps (corresponding to when the emails were generated) are around 21:18 GMT, but the arrival timestamps are around 21:49 PST, about 8 and a half hours later. And that's about how far apart our emails arrived. I imagine more are in the queue.
(And yay crapflooders for making it impossible to format things usefully in Slashdot comments.)
As far as passwords go, I'm not worried about anyone actually hacking my Kickstarter password. It's a password unique to Kickstarter, and it was generated at random.org as a 13 character mixed-case alphanumeric password. Good luck reverse-hashing that. Even if you do, it won't get you much.