Let's face it and stop being naive: the Caucasus is Russia's backyard. The whole region holds an immense economical and geostrategical value for the ex/new/never ceased to be superpower. In the old times, when the vetuste, archaic Soviet Union exported almost nothing, we still could think that the problem was most of all ideological. But not anymore. It's about money.
Were the Americans really expecting that the Russians would let Tbilisi regain total control of the region? No, they weren't. They were just trying to stir things up a little, maybe to test Medvedev's strength, and at the end it's up to Europe to try to calm things down and pick up the pieces (one quarter of our energy depends on it) . And up to the Georgians and the Ossetians to bury their dead. It's "those Washington bullets again". Or Moscow bullets.