Twitter in Drupal. It works. Simple. Well, sorta.
This comment got me most of the way to working:
http://drupal.org/node/410284#comment-2343572
Except I needed to patch the twitter module, and I don't recall where it was. It's in the drupal comments somewhere. I'll edit it in.
This is on Drupal 6 still, no idea if it works on the newer 7
Ok, so per the link above, you have to be using the older Oauth module. You need to register your drupal install as an "application" with Twitter (for Oauth to work) and you then need to configure Oauth to use the secrets Twitter gave you.
It still won't work after that until you apply the patch from here:
http://drupal.org/node/966748 (comment #14 has a .patch file, or you can manually edit it in (comment #4)
Once you've done that, your users can register with twitter. The home page uses a view pointing to my twitter feed, for example.