There is no such thing as a free lunch - everybody knows that. But when it comes to software, we tend to think that it is (or should be) free. Free as in free beer, not as in speech, quite contrary to what free software philosophy says. But software is not grown like crops in the field, it requires long hours of work from people who create it. Many people write software and release it under one of open source licenses in hope that some day it becomes popular; but when it finally does, it turns out that its development takes so much time that you either have to drop it or start working on it full-time.
This is what recently happened to Clojure. Rich Hickey, the creator and main developer of this fascinating programming language announced his financial expectations towards individuals and businesses who benefit from it to fund its further development. I hope Rich gets enough financial funding to continue his work on Clojure. If you use Clojure in your development, maybe you should also think about donating.