Well he voted for the FISA Amendments which would seem to suggest that as President he intends to continue Bush's policy of spying on Americans, for one. Another example would be his voting for bailing out failed businesses, which the Constitution does not give the federal government the authority to do in the first place. To add to that, the bailouts were voted on by the Senate before they were approved by the House despite the Constitution saying that all money appropriations must first pass the House. Whether he agreed with the bailouts or not, he should have voted them down based on that fact alone.
My guess would be that, as President, he intends to circumvent the Constitution as he sees fit, just as he has done as a Senator.