I've wanted something similar in the past. eyeD3 0.7 supports a plugin interface that would be perfect for this tool, it would also reduce some code. I could see such a plugin that supports some options allowing the user to customize the art file names to use (e.g. cover, instead of Folder). If you'd like to see this in eyeD3 I recommend writing this as a plugin. Otherwise I'll leave this here, for reference. Thanks.
Was actually more interested in including something like this in a section like "User Contributed Example Programs". I generally prefer the complete control of calling the eyeD3 library from a python script, and some example code would have speeded development. Other folks may just need a quick example of some of the calls to eyeD3 to get started quickly. Having said all that, I can take a look at what it might take to create a plugin. Thanks.