Recently Lucene and SOLR development is merged . Following this announcement, SOLR 3.1 is released and SOLR version number is synced with Lucene. Here is a small tutorial video about SOLR:
You can also check the latest reference guide from here.
You might want to watch the interview with Grant Ingersoll, a Apache Lucene and Solr committer and co-founder of Lucid Imagination about the merging of Lucene and SOLR.
LINKS
Lucene and SOLR Merge
SOLR 3.1 is released
SolrCloud is on the way
Solr Reference Guide
