I don't know if this has happened before, but a bot is up for RfA.
The bot is there to clean up redirects and to delete pages with broken redirects (ie the redirected page was deleted or has been moved). It's pretty uncontroversial and the RfA will probably pass--at least at the point it's at right now, but it does, once again, open the door to a lot of interesting questions.
For example, what happens if somebody hacks the bot and it goes on a deleting rampage. How many pages can it delete before somebody figures it out and blocks it?
Also, if they have a bot that does this, then what about a bot that analyzes contribs and blocks anybody who adds (for example) "ERIC IS A FAG!" to an article?
How about replacing the ARB-Com with a bunch of bots?
I'm just wondering if they really have thought this through....