Earlier today, Georgia attacked South-Ossetia in order to regain this separatist province. This will probably lead to war between Russia and Georgia, and Georgia is already claiming that Russian jets have bombed Georgian targets. Meanwhile, Vladimir Putin has vowed to retaliate against Georgia, for some Russian soldiers have allegedly been killed, and besides, most South-Ossetians have Russian citizenship.
The independence of South-Ossetia from Georgia is not internationally recognized, and neither are the referenda in which the overwhelming majority of South-Ossetians voted for said independence. Btw, North-Ossetia is a part of Russia.
We’ll have to see how this develops, but this might become very bad, if very recent history is anything to go by. Another separatist Georgian province is Abkhasia. In 1993, the Abkhasians won their own war against Georgia with some outside help. The non-Abkhasian population fled or was ethnically cleansed. Up to 10,000 people died, and up to 300,000 were forced into exile. There also is no telling how far Putin might go; the Second Chechen War also has been very bloody.
Meanwhile, some historical background (and very convoluted background at that):
Also, don’t miss the Georgian Affair from 1922, it shows just how complicated things are in the Caucasus region, and no, nobody there thinks that there should be some kind of statute of limitations on revenge, claims to independence or respectively the reconstitution of former statehood as it had been in centuries past.
Update: Russian troops have entered South-Ossetia, two Russian jets have reportedly been shot down.
Update II: Now Abkhasia (or Abkhazia) is threatening to open a second front against Georgia
Their foreign minister points out that Abkhasia was forcibly integrated into the Georgian Soviet Republic when Stalin, a Georgian, led the Soviet Union.