In the US House, 2006 elections, Kilroy was up 12 points in the polls, and lost in a close election. The same thing happened with Eric Massa. In 2002, similar things happened with Roy Barnes and Max Cleland... though there is the possibility of electoral fraud.
South Ossetia was invaded first by Georgia. This is a fact that everyone agrees on. Well, Georgia calls it 'restoring constitutional order to a renegade province' (or something like that), but the meaning is the same. That's why the fighting was in South Ossetia (around its capital) until Georgia began pulling out.
I don't agree with the Russian invasion of Georgia proper... but the overall pattern of this is something that most political analysts (which I am not, obviously) could have predicted. Russia sees Georgia as a threat. Russia wants to project its strength. So Russia isn't going to let Georgia embarrass it by regaining South Ossetia - and it will probably take the opportunity to use the casus belli to get rid of Saakashvili, whom it sees as a threat. I don't agree with its actions, but it makes logical sense from Russia's point of view - realpolitik is a must for understanding today's world.
Russia sees the Georgian president as a hyper-belligerent warmonger who's going to be a thorn in their back. So this provides them a convenient casus belli to oust him (and perhaps install their own puppet president), while sending a signal to the rest of eastern Europe that the Russian Bear is back.
In short, Saakashvili was hoping to quickly seize South Ossetia with tacit support from the West, and have it be a fait accompli before Russia could move in. He miscalculated and overplayed his hand.