I remember reading that Cheney had them remove all wireless functionality from his pacemaker because they were afraid of the potential of someone using it for assassination.[1]

[1]http://abcnews.go.com/US/vice-president-dick-cheney-feared-p...

EDIT: Also, no you shouldn't release a pacemaker 0day. As others have said, expose it without releasing details. Makes for a nice demo.