Thanks for the link! I did think that someone else must have discussed this phenomenon before :) I just now read the blog post, but haven't had time to read all the other references and posts linked by it.

As far as the blog post goes, they pretty much do the same thing I did - describe the phenomenon but not explain it. (Not that I can explain it either!)

The only thing we can say with confidence is that these constructions are tricky to parse and many people have differing opinions as to what the "right" interpretation is!

:)