It started as Lucene, but is quite different by now as Jim (http://friendfeed.com/jim http://friendfeed.com/jim) had to create all of the real-time indexing and

It started as Lucene, but is quite different by now as Jim (http://friendfeed.com/jim http://friendfeed.com/jim) had to create all of the real-time indexing and standing query support (at any moment, it is simultaneously executing thousands of queries).