While I'm still quite the Smalltalk beginner, in trying to learn how a few things are done in GNU Smalltalk I have tried to jot a few things down.

First I wrote a small and very simple (1 file listing) echo server using the TCP package directly:

http://sblinn.jottit.com/gnu_smalltalk_simpleecho_tcp_server

Second I wrote a small and very simple chat server, which adds to the above by using a few classes, a few different file listings, and (of course) a bit of "state" on the server side to allow named connections and multi-person chat: