One of my oldest clients is switching to a new technology stack. After many years of using AOLServer, OpenACS and Postgres as their preferred basis for applications they have switched to using nginx, Redis, node.js and Postgres with plv8.
I'll be talking about some of this, especially the use of Redis with Postgres, at pgcon. in May.
I can't say I really like the node.js style of programming, but needs must when the devil drives. One thing worth noting is that there is quite a good node.js driver for Postgres, and that the maintainer was very responsive in merging in a patch I sent. I've sent in another one (to fix a bug connecting to Unix domain sockets) and I hope it too will be picked up very promptly.