I can't find the quote now. It would take forever.

But I asked specifically what happened to the Sparky project. He said it underwent some revisions and will integrated into 1.9.

If I understand this all correctly, UltraPeers house cache lists so that repetitive/similar/same searches are NOT repeated. The cache keeps a recent record and sends results back accordingly. So, when 50 people search for the same thing, only the initial search will be made, and the rest is a copy of the search that has just occurred.