Always ship trunk
Always ship trunk: Managing change in complex websites (pdf) talk by former Flickr engineer Paul Hammond. He basically recommends using configuration management system for live production code. Another Flickr engineer (ross) agrees with him: Flipping out.
Corresponding HN thread is interesting, as usual. For example, bdb told about Apache Zookeeper, neilk posted about “a more wide-ranging talk” by Paul Hammond and John Allspaw – 10+ Deploys Per Day: Dev and Ops Cooperation at Flickr: