Well, here's some insight:
Georgia has been wanting to take back South Ossetta for quite a while now after they separated from the country. Georgia finally pushed a little too far and Russia got pissed. Georgia has a standing army of 37,000 US and NATO trained troops and technology purchased from the US. Russia has a standing army of 1.1 million. The key here is Georgia is a small nation and Russia can only approach from one sector: the north. Georgia's highly-trained 37,000 troops can easily hold off upwards of 50,000-70,000 Russian troops. Georgia knows its landscape. Its like trying to invade Switzerland - high mountains and a small country with a well-trained military. This could go on for quite a while, and it probably will. Neither side will back down.
Russia wants NATO and the US to send reinforcements to help Georgia. Why? Russia's military equipment is outdated - the country wants an excuse to update and engineer next-generation equipment. They chose a very cunning time to approach Georgia. Right now, the world has its eyes on the Beijing Olympics and the US is concentrated on domestic elections.