This set of slides, Slides: Scaling Massive ElasticSearch Clusters, comes from Rafal Kuc at Sematext. Rafal gave this talk just a day or 2 ago at Berlin Buzzwords.
ElasticSearch does not have as large of a community as SOLR, but is really gaining a lot of mind share and is receiving a lot of converts. ElasticSearch is really a great project. Check it out when you get a chance!