[arximboldi]

  > Intuitively Lisp might be a secret weapon for startups, but not for open source 
  > where the communities of the mainstream choices are more productive, simply because
  > of popularity

Open source is not a popularity contest. In fact, open source, and specially free and libre software, is a great place for leftfield technologies to flourish. In fact, Lisp had a place in free software before Github even existed, with various flavours being the scripting language of choice in popular projects like Emacs, Gimp or Gnome.

It is rather in the proprietary corporate world where there is often resistance to adopt languages outside of the mainstream. The more supply of developers for a technology is available, the lower cost of labour. It's hard for the merits of a technology to argue against this fact in the face of management.

[coldtea]

Nobody who uses it really likes Emacs list and Guile didn't get far. Not the best success stories to give.