When I was unable to post to Twitter from my blog tonight, I found a very new thread on drupal.org discussing the issue: the Twitter API changed again!
I am only using the Twitter module on Drupal 6 sites right n ow, I took two of the fixes and combined them in a patch for the 6.x-3.0-beta9 version. Then MinhH submitted new code that only requires a change in one place.
here's my latest patch for the 6.x-3.0-beta9 version
since the Twitter API is constantly changing, and the module is not very stable, always read the thread carefully to make sure you are applying the latest patch! Others have cleaned up the code I added from MinhH, and created a patch for the 6.x-3.x-dev branch which makes sense (however I suspect that 6.x-3.0-beta9 may be ahead of the -dev branch, and it's not a branch provided in the project's Github). Anyway, Open Source rocks, Murray!
and because my Twitter RSS feed URL was also broken, I found this post
which provides an update to the URL format: