So here is a little background on who's who in the Georgian crisis:
Mikheil Saaskashvili is the current President of Georgia. He first came to power following a bloodless revolution that overthrew dictator (and former Soviet Foreign Minister) Eduard Shevardnadze. Saaskashvili has since resigned and then been formally elected in a special election. Saaskashvili's political party the United National Movement is a pro-western, reformist, pro-democracy party.
Eduard Kokoity is the President of the Russian puppet state in South Ossetia. He is not recognized as a head of state by any government other than Russia's. He is a former wrestler for the USSR national team and lead the local Communist youth organization back before 1989. From 1992 to 2001 he was a "businessman" living in Moscow.
Sergei Bagapsh is the President of the Russian puppet state in Abkhazia. Like Kokoity, he is an old CPSU apparatchik and leader of the local Komsomol chapter. Also, like Kokoity, he spent much of the 1990s in Moscow as a "businessman."
Vladimir Putin is the Prime Minister of Russia. While he resigned his position as President it is widely believed that he continues to be the true power in Moscow. Putin's CV includes a career in the KGB where he started in the division of the KGB responsible to monitoring and persecuting domestic dissidents. He eventually transferred to the foreign affairs section but most of his posting were of the sort you'd expect to see for a political enforcer rather than an international man of mystery. For example, he finished his KGB career in 1990 in Dresden in the former East Germany (not a posting you would expect for a foreign intelligence guy but a great place for a political enforcer). Yeltsin appointed Putin to be the head of the FSB - the agency that took over the by then defunct KGB's domestic operations. His presidency has been marked by crack downs on the dissident press.
Dmitry Medvedev is the current President of Russia. Before Putin got him the Presidency, he was Putin's chief of staff and sometime member of Gazprom's board of directors. His entire career has been tied to Putin's and he's mainly known for his loyalty to Putin.
Gazprom is the formerly state owned natural gas company in Russia. They control 16% of world natural gas reserves and dominate the natural gas market in most of Eastern Europe including in several EU member states. The EU gets about 25% of their natural gas from Gazprom.
The Russian Army is still one of the largest and best equipped in the world. Their air force is also very strong.
The Russian Black Sea Fleet is based in another country, Ukraine. Ukraine has threatened to keep the Russian ships out of their ports if the Russians launch naval attacks on Georgia from the Ukrainian bases.
Victor Yuschchenko is the current President of Ukraine. Like Saaskashvili, Yuschchenko came to power at the head of a pro-democratic, pro-western reformist movement. He was famously poisoned during the election. Rumors of who is responsible for the poisoning range from rival Ukrainian politicians (including the current Prime Minister) to the Russian FSB.
Yulia Tymoshenko is the Prime Minister of Ukraine. She was one of the leaders of the reform movement that put Yuschchenko in power. Their political alliance is a strained one.