RealClearPolitics just linked to Samantha Power's excellent New York Review of Books piece about the foreign policy Democrats ought to adopt--incidentally, it's a review of our executive editor's book U.S. vs. Them.
Echoing Obama's new ad campaign, Power says Democrats should emphasize:
The New versus the Old. Democrats should argue that their foreign policy is particularly well suited to meeting today's unconventional threats--those that cross borders. Meeting such threats will sometimes entail using military force, but it will almost always require mustering global cooperation. Here the Democrats must point to the security consequences of the loss of respect for the United States around the world: the U.S. requires the assistance of others to aid it in combating terrorism, halting nuclear proliferation, and reversing global warming.
It's well worth a read.