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The manager does need to exercise sound ethics. As raubin has said here, a manager's success can be seen by the career development provided to his/her supporting staff.

Yes it's company property, but there's still something to be said for self-preservation in a tough job market.

I say compile all the messages you sent to you immediate supervisor (the one likely taking credit for your ideas and efforts), and go over their head to the powers that be. I say this because if your instincts tell you your days are already numbered, you probably have good grounds to feel that way.

More bluntly put, through him/her under the bus. You;ve already been stabbed in the back so there's not much else to lose if it's looking grim.