I'm neutral on this idea.  I would much rather focus on making sure that the various modules (such as pdb or tarfile) which have useful command-line functionality document that clearly and uniformly, but as part of each module's library docs.

I don't think that a list of all modules that have such behavior really belongs in the stdlib docs, but if someone wants to add it and keep it up to date I won't object.  Just understand that whatever is documented must preserve some sort of backwards compatibility.  And don't repeat the same information in two places.

Maybe the blog post that started this is actually enough?  Or if something more official is needed, perhaps a how-to document?