Francis Irving sent me a note about his work on a new Rails search plugin, acts_as_xapian. It uses the Xapian engine, which is a C++ indexer similar to Lucene. A particularly neat feature is built-in spellcheck.
I still plan to benchmark all these plugins on the Wikipedia dataset…it’s been delayed by the new job. If anyone has a big piece of iron I could use for a couple weeks I would appreciate it (16GB ram, hundreds of GB of free diskspace, no production load).