On 2010-10-24 I cloned cl-twitter's darcs repository of Ian Eslick's common lisp twitter package..
The package in the repo no longer compiled. After getting it to compile I found that it did not work with twitter's oauth protocol which at that point was the only way to get authorized access to twitter.
It turned out that all the pieces were in place to enable the open authorization protocol. After doing a quick review I found that about half of the twitter api was more-or-less covered.
I split the code into three pieces :
Consult the respective readme's for more information.
The rest api is fully covered.
The streams tweets resources have not been implemented.
The twitter repl client is functional. What's missing are good pretty printer outputs for some twitter resources.
See the README for that module.