Article on using SolrCloud for low latency analytics. Example configs on GH.
This conference looks really interesting and is probably worth keeping an eye on.
Lucene/Solr Revolution 2013
The Westin San Diego
April 29 - May 2, 2013
Short howto on using jmxtrans with Ganglia for monitoring ElasticSearch and SolrCloud.
As the comments point out, similar metrics/stats can be pulled from the ES REST API, but this is a nonetheless useful howto.