There will be no military coups in the United States.
What could (but won’t) happen is this:
After the Electoral College votes are counted and Obama wins (hypothetically), written objections to his qualifications to serve can be submitted, so long as each objection is signed by a Senator or a Representative.
Then the objections are submitted to the Senate and House, respectively, for their decision (however that is made).
If they find the President-elect is not qualified, then the Vice President acts as President.
http://tesibria.typepad.com/whats_your_evidence/2008/09/mr-bergs-standi.html
I never suggested or advocated a military coup taking place. I was using that as an example of what would have to occur in order for a President-elect Obama for being sworn in.