Adding to Jon's comments:It looks like the katta searchers have support for distributed idf. Not sure about solr (though seems to be talk of it around SOLR-303). My guess is that soon after you get searching working, you'd miss it if it wasn't there (Results warped by uneven term distribution across your shards).
I for one would be very interested in helping such a project along. Where are you located Tim?
St.Ack
