Microsoft adCenter is having some problems keeping their reports up to date. If you look at the adCenter dashboard and see that your campaigns aren't getting any impressions from yesterday, it's probably because the report system is not up-to-date.
Look very carefully at the bottom left of the dashboard. Right now, as of 9:30am PST, Feb 13, it says (in a tiny gray font):
Performance data last updated on 2/12/2007 7:00:00 AM Pacific Time (GMT - 8)
That's why I don't have many impressions for my campaigns from yesterday! The data is over a day old! I'm glad it's that, and not some editorial action, or billing problem.
I called Microsoft adCenter support and they said "they are working on it". While working, they should make the "last updated" message a lot more prominent when there's a big delay.
Also, why no message on the adCenter blog? They usually put up boring notices of maintenance downtime on that blog, and the reporting has been broken for about 2 days now.
PS: Why does the adCenter blog need a cheesy mediaplex banner ad on top? Is that helping your credibility?