I've Googled around a bit, and haven't found anything that talks about this issue, so I humbly submit my problem to the Twitter wizards.
Here's the problem - when I call the API function update_profile_image, the upload succeeds, and Twitter returns status code 200. If I go to my actual profile image page (http://twitter.com/ account/profile_image/pianoben), the updated image (let's say "O_RLY.jpg") is present. However, the rest of my profile still retains links to the scaled-down version of the former profile image, i.e. instead of "http://<amazonWS>/o_rly_normal.jpg", everywhere a profile image is needed still links to "http://<amazonWS>/ old_picture_normal.jpg". The latter is the URL returned as profile_image_url when calling /users/show/pianoben.xml. I'm pretty sure I've got my library code down pat, as the image itself verifiably uploads - it looks like Twitter is barfing on updating my user info after the API call completes. It is worth noting that none of this happens if I upload an image via the web interface. Has anyone else encountered this? What did you do to solve this? Or is this a Twitter bug? Thanks, Ben