I was part of two failed attempts at personalizing news/ creating communities of topic expertise around news. Both ended in the many tens of thousands of users, and acqui-hire talks (not with either Zite or Flipboard).
My thought on the tech was it was consistently good, the product was simple and easy to use, and worked very well at aggregating subject based articles (I'm sure there was much more behind the scenes that would have scared us at the time)...
we were trying to do not only the smart aggregation, but create hooks into reading communities to encourage an atmosphere like HN - instead of mystical karma points, you would see btrautsc; expert in X, knowledgable in Y, novice in Z and so forth. Like I said, it ultimately died a timely death.
For whom did you work in a previous life, out of curiousity?