The article was first published on Sesat Weblog. As the whole site went down several days ago, I retrieved the content from the Google cache and posted it here for perservation.
Update: Original site is up again.
Sesat has published a nice in-depth report on why to move from Fast to Solr. The article also includes a description of the steps taken to move over as well as several statistics:
http://sesat.no/moving-from-fast-to-solr-review.html
On a related topic, the following article details, where Apple is using Lucene/Solr to power it’s search. Spoiler: Look at Spotlight, their desktop search, as well as on the iTunes search with about 800 QPS.
Update: As the site above could not be reached for quite some time, you should either look into the Google Cache version.
Grant Ingersoll has posted a very interesting interview with Ian Holsman on Solr at Relegance, now AOL. It describes the business side of the decission to switch to an open source solution, provides some inside on the size of the installation and details which technological reasons have driven the decission to switch from a proprietary implementation to Solr: