It's, basically, quite a complicated situation.
The situation has been escalating for just over a week after Georgian forces stormed South Ossetia in the hope of claiming the territory. Several paramilitary troops from South Ossetia were killed early on in the conflict.
Things took a turn for the worse when Russia decided they would press though North Ossetia, across the Russian-Ossetia border and towards the south—perhaps an understandable move considering there are many Russian citizens in the area. Moscow, specifically President Medvedev, has stated that:
"According to the constitution, I, as the President of the Russian Federation, must protect lives and the dignity of Russian citizens wherever they are. Those responsible for the deaths of our citizens will be punished."
Now, I can see where President Medvedev is coming from on this one. The Georgians acted pretty irrationally and spontaneously, bar the permit by NATO at Bucharest, over an area which they knew Russia would retaliate over. It really does seem like a little bit of a suicidal plan for Georgia. Let's give some perspective on that with a brief comparison of military capabilities (taken from the Wikipedia article):
Population of Georgia: 4.6 million
Population of Russia: 140 million
Standing army of Georgia: 18,000 personnel
Standing army of Russia: 1,037,000 personnel
Georgian tanks: 128
Russian tanks: 23,000
I think you see where this is going. If anyone can offer rationale behind the Georgian's tactics, please feel free to explain. In fact, let's make that a question to you all.
"Who knows a reasonable explanation for why Georgia would actually try and fight against the Russians?"