The Twitter Engineering team (@twittereng) has just achieved an impressive 3x performance improvement for Twitter search queries, largely, it seems, by replacing Ruby-on-Rails web applications with new applications built on Java, coupled with a switch from MySQL to Lucene for the data store.

Priocept has recently been working with Apache Solr, a kind of "Lucene on steriods", which fast approaches a NoSQL database when used for applications such as geodata and automatic data categorisation (as used on eBay).