I know the OP was looking at ARM for servers, but I've used node.js on a Raspberry Pi to do IoT sort of things - there are a few libraries that make controlling

I know the OP was looking at ARM for servers, but I've used node.js on a Raspberry Pi to do IoT sort of things - there are a few libraries that make controlling GPIO pins pretty easy, so combine that with node.js and you've got a pretty enjoyable hardware development experience. At the time, though, getting node working on the Pi was a major PITA. There weren't any official built binaries available, and a number of bugs kept me from successfully compiling it. I eventually found a binary that someone else had built, and from then on it was smooth sailing. But I'm glad to hear that it's become a first-class platform now.