To export your Google Maps starred locations:
Go to Google Bookmarks: https://www.google.com/bookmarks/
On the bottom left, click "Export bookmarks": https://www.google.com/bookmarks/bookmarks.html?hl=en
After downloading the html file, run this script on it to generate a KML.
It's hacky and doesn't work on all of them, but it kinda works.
I'm using (part of) this at https://github.com/marado/stars-to-addresses . I am assuming I can, since there's no LICENSE information for this gist, but I wouldn't mind getting explicit permission.