Erlang web frameworks survey [closed]

Question

(Inspired by similar question on Haskel)

There are several web frameworks for Erlang like Nitrogen, Chicago Boss, and Zotonic, and a few more.

In what aspects do they differ from each other? For example:

1. features (e.g. server only, or also client scripting, easy support for different kinds of database)
2. maturity (e.g. stability, documentation quality)
3. scalability (e.g. performance, handy abstraction)

main targets

Also, what are examples of real-world sites / web apps using these frameworks?

EDIT: Starting a bounty in hopes that it will get some conversation going