High Scalability Building bigger, faster, more reliable websites.

This article explains how Outside.in, the local social network and aggregator, scaled up its service and moved from PHP to Ruby on Rails (they moved maybe because Ruby code seemed to be more maintanable that PHP code?).

The whole article is here on EngineYard blog.

In a recent project, I utilized RoR's cookie-based session storage to shard geographically distinct user groups. My technique for doing so was unique and, although it was a premature optimization, it is none-the-less an idea worth exploring.