I received this email a few minutes back. It is sad to see this happening and that too on such short notice. Used to use it along with Adsense, and it was the only good alternative.

I am certainly going to miss the feature where they automatically swapped their ad-code to any competitors if theirs din't cross the minimum CPC threshold.

If I recall correctly, the CEO/Founder of Adbrite is a member of HN. Maybe he can shed some light.