On October 12th we finally released version 4.0 of Apache Solr. See http://lucene.apache.org/solr/solrnews.html for the release announcement. So if you have been reluctant to start using 4.0 beta, now is the time to upgrade. You will enjoy instant improvements in performance and disk/memory footprint just by upgrading, not to mention all the cool new features such as SolrCloud and more. Enjoy!