Lukyas' point is relevant, but wrong. The analogy is Kosovo wanted to secede, Serbia wanted to violently keep them from doing so, but outside powers forced Serbia to let them go. Someone using that logic would say the separatists want to secede, Georgia is saying no, and is trying to violently keep them from doing so.
The problem is, of course, Russia has been fomenting this particular rebellion, if you want to call it that, for quite some time now. They want the secession to take place so that Russia can absorb them, be it officially or unofficially. The US is trying to make Georgia a NATO member (and has trained and armed the Georgians), Russia is saying, "**** that" and we're basically using Georgia as a proxy to get at Russia (keep them in check, basically) while Russia is using South Ossetia as a proxy to get to Georgia and reclaim some of the land they lost after the USSR collapsed.
You can say Russia is right to "retaliate", but Russia didn't belong in South Ossetia in the first place. When you poke and prod an animal, no matter how small it is, it's going to lash out at you. This is what Russia has done, but being the polar bear that they are, they can basically walk all over Georgia, and that was probably the plan from the very beginning. Make them strike first, use that as an excuse to take what you want, and move on from there.
