My first reaction was, "Why does that dolt want to take over South Ossetia? Does he think the Russians won't intervene? Or does he think the Americans will intervene on his behalf?"
The historical background is that Ossetia, and the other autonomous areas Georgia attempted to invade, have been independent and at odds with Georgia since before the Russians showed an interest more than two centuries ago.
The economic context is equally plain: the Russians furnish Europe with oil and natural gas. With Ukrainian independence, Russia lost most of her Black Sea ports; Georgia provides an avenue for Caspian oil while leaving the Russians out, which gives other major interests (can you say "Exxon Mobil?") an opportunity to deal from a position of dominance.
The Georgian President clearly decided to end a long standing border feud, which may very well have included Ossetian irregulars taking advantage of Russian protection to engage in provocative acts. Unambiguous information about the deployment of troops and their potential on both sides is lacking; Georgia claims to have withdrawn, and to have been invaded by Russia, but, given the distances involved and the effective range of modern weapons, "withdrawal" and "invasion" mean relatively little at this point.
The Russians, to their credit, have already called an emergency meeting of the Security Council to intervene, which the U S later urged as if it hadn't already happened. The French are working "on the ground" to appeal to both sides for a cease fire. And contradictory statements as to the facts come from both sides, as civilians die, and flee, and weep.
"Great power" theory, developed in the late stages of Western Imperialism, does allow for the sponsorship of small, relatively weak states by the powerful. It does not follow that the powerful should choose whom they will sponsor foolishly, with only one factor predominating. Especially, it does not allow the weaker state to determine the course of the Great Power, by sending a brigade in support of other foolish adventures, nor to entice the Power into a conflict far greater than the interests at stake. The morons directing U S foreign policy appear to be committing both these errors here, at a time when their ability to back up such idiocy is grievously lacking.