I think you need to have a few languages in your arsenal(but not too many), I like php, python and clojure for example. This doesn't make me an expert to all of

I think you need to have a few languages in your arsenal(but not too many), I like php, python and clojure for example. This doesn't make me an expert to all of them but given the proper time I am able to create any app in those languages. Apart from this, it's true that you need to invest time in learning how to architecture staff... unix, networking, programming internals, keeping yourself up to date with whats going on in chaching, queuing, databases. Patterns and solutions to real life problems are have common solutions to any language/platform.