Actually, I think "printing money" also requires an increase in the debt ceiling. The money printed by the Fed still counts as debt. The treasury still produces a bond and sells it (thereby increasing the debt), it just happens to be the Fed that prints money to buy it.Whilst I think it's highly unlikely that the US will default, I don't see it as a given that the debt ceiling will be raised.
I'm sure Mr Bernanke would be more than happy to print some money to tide the US over.
Also, there's some debate over whether or not the 14th amendment would allow Obama to unilaterally increase the debt ceiling if it can't be done in the "conventional" manner:
"Section 4. The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned."
http://en.wikipedia.org/wiki/Fourteenth ... nstitution