I think the problem with the question and the variance in the answers to it is that we are all approaching it from the views we have through our own biases and filters. Someone in management (an MBA, no doubt) described it as a case where we are all wearing sunglasses of different colours. The scenario and ensuing courses of action are very situational.
With respect to the OP (nutengineer) stating that he / she is somewhat of a senior manager, I assumed, taking that on face value, that the information he / she had received was probably dependable - more than just hearsay. If one was to subsequently be faulted for leaking the information in the first place, then that fault properly resides with those who informed nutengineer, not with nutengineer. Playing the scenario out, that is precisely the message that I would convey to HR if I was ever taken to task on it.
To me, rumours, hearsay etc. are cancerous and destructive in the workplace. The best way to kill one and get on with things is to let the subject of the rumour know about it. That gets things out in the open and forces everybody's hand. A work culture is only as good as what you create. You can choose to live and work in a clandestine, back-stabbing, double-agent mentality, or you can choose to be forthright, honest and embrace the spirit of team play.
Sorry...I have seen too many very good people get "screwed over" by their bosses or managers in situations similar to this, and I cannot with clear conscience turn a blind eye to things and pretend I don't know about it when a friend is involved. The only difficult decision in my mind would be "how" I told the person - word choice, environment, etc. I think the people I work with (or "for") now understand that, and they respect my ways by simply not confiding in me the things that would put me in such feelings of conflict.
Regards,
SNORGY.