[davidw]

Yeah, but that's harder when everyone knows Erlang, and one guy goes off and writes something with, say, Django for fun.

[Revell]

But if someone goes "lone wolf" and writes an application in a language he or she chose without informing other members of the team/organisation something else might be going wrong in the chain.

I get the idea you're trying to convey here but in the case of a well-organised team/organisation that won't really fly as everyone will be involved at some point and choices are being made together.

[joevandyk]

Pair programming comes in handy here.