The powerful PodPress plugin for WordPress seems to have a problem with the new post revisions feature of WordPress 2.6. For many the solution has been to disable the post revision feature — but I happen to think that the post revision feature is a good thing.
Go here for a post by Andrew Ozz that explains how to fix the problem. Note that if you're using PodPress version 8.8 you'll find the fix in the comments section of that post.