MediaWiki.org has just been a victim of the 'Commons deletion issue'. An image from the Crystal icon set that was prominently used in many navigational pages, including the main page, was deleted from Commons and suddenly MediaWiki.org is full of broken images. The deletion was valid (it was a duplicate file) but the fact that the actions on SiteA can affect SiteB so radically is really rather worrying...
A technical solution would be for people deleting files on commons (for this kind of reason) to replace the page with a redirect page, and for these redirects to be resolved by MediaWiki when linking to a shared file. This won't solve all problems of course, but it would help for this kind of situation (or e.g. a GIF being replaced by an SVG). Of course, I'm sure there are many ways this could be abused as well...
I don't know if anyone has any suggestions to deal with this kind of problem, or even if it has already been recognised as an issue. The non-technical answer is, of course, to copy the commons images to the local wiki, but that kind of defeats the point of commons, doesn't it?
- Mark Clements (HappyDog)