The US military has put forth something known as "Full Spectrum Dominance" in which America is to retain a position of global domination through military force in all domains. Think tanks like PNAC have indicated the desire for policy makers to keep the US as a global hegemon. The US has been acting as an aggressor, rogue nation for years, with military bases across the globe, and illegally waged "kinetic actions" in places like Libya. What is going on with Russia, Georgia, and the Ukraine, is part of a pattern of covert destabilization tactics used by the US, either with black ops or the funding of "pro-democracy" NGO's whose real intention is toppling leaders in the interest not of average Americans, but the corrupted American elite class.
It is way soon to tell if this new events that have taken place between Russia and Ukraine along with the rest of the world has started another version of the cold war like we had seen in the past. It is almost irresponsible to come to a judgment so fast.
I do not believe the Georgia-Russia conflict started a 21st Century Cold War. I do not believe the United States will interfere with Russia's decisions. I believe the United States will warn and make light threats, but they will not act. America doesn't have the strength or the economy to continue in military battles.
No, I believe that the situation, while tense, did not start a second Cold War. For one, there aren't too many proxy wars being fought throughout the world (at least, not for those two countries). You also have to realize that the Cold War was about other things as well like space travel and atheleticism. This is nothing like the Cold War.