UPDATE:
i think i have a solution without contact with support,
correct me if i am wrong.
i installed the “wordpress.com stats” plugin on a wordpress blog i host myself (besides wordpress.com), after entering my API key from wordpress.com.
i got the option to ‘Add new blog to my account’ and ‘Replace an existing blog’.
see screenshot
to prevent ‘<b>this info is passed somehow to Google</b>’;
on wordpress.com/profile/?edit=true on the bottom of the page you can change options of your “Profile Layout”, with on the right select from “My Blogs” if they are visible.
