Twitter on Scala: "the production issues that led them to consider Scala in the first place, what issues they ran into using Scala in production, and how Scala affected their programming style". Disclaimer: I know *nothing* about Scala, though it sounds like enforcement of functional programming (and its effect wrt concurrency) was the big win here...
Google App Engine got Java - wooo! Very exciting, I've been playing with this over the weekend and the tools look decent (though, ahem, my first real GAE project won't bloody deploy). I think this'll make a big difference to how we build and host server-side products long-term...