Mar 23 2016
Another related thing I've been noticing: PageImages seems to strongly prefer images that are square-ish or portrait-sized. This makes a lot of sense for thumbnails in search, but not so much in Hovercards. Often suitable wide images, like logos, are skipped for this reason (even if they're PD-ineligible). But Hovercards can handle wide images just fine.
I've also seen a report where an image of the wrong person was displayed for a biography (there was no image of the person in question, but an image of another person was extracted from one of the navboxes.) Can't find the link right now.
Feb 15 2016
Clearly, merely knowing the pageimage data is fine. A more realistic scenario would be that the 3rd party re-user does not realize that the returned page image may be non-free (Wikipedia is marketed as being free...) and then displays that image in such a way that it no longer passes the (legal) fair use test.
Jan 27 2016
Jan 26 2016
Jan 21 2016
Jan 20 2016
Stop making this sound more complicated than it is!