Grant Ingersoll – Apache Solr 1.4.0 Offically Released:

"New Solr 1.4 features include
- Major performance enhancements in indexing, searching, and faceting
- Revamped all-Java index replication that’s simple to configure and
can replicate config files
- […] Dynamic search results clustering via Carrot2
- Multi-select faceting (support for multiple items in a single
category to be selected)"