ahh.. i wondered when that would come along.

I had a thought that relevance should be computed like a "stream database", but with an index rather than a data store behind it. Maybe something like Streambase - but written in Clojure - on top of the lucene index.

Take it one step further, where the entire index is expressed as s-expressions (i'm a bit out of depth here) - you can basically write a mapreduce job on the index.

However, I'm not so sure that computing relevance can be parallelized - i.e can it be broken down as opposed to be computed as a global problem ?