yeah micro-organisms are simple, and uh... primitive but that just means that many of them are just waiting to start given the right circumstances no matter where they crop up
volcanoes, undersea vents, in poisonous organic pools of sulfur and phosphorus, embedded in permafrost, all of these places are less hospitable than the water in Vostok, what is of significance is that if life is found there then it may also be found in other similar water bodies with extreme pressure under moving sheets of ice... on moons in the solar system
posted a link to a spectrographic analysis of space dust somewhere earlier, where it emerged that interstellar space dust is made up of bacteria sized particles, this is a much more digestible Wired version! >> Howard Hughes' Nightmare: Space May Be Filled With Germs
and last year some Hyderabad scientists sent up a weather baloon into the highest regions of the atmosphere, and found clumps of living cells that seem to have drifted in from space this is a much earlier story on similar researches >>> Scientists Say They Have Found Extraterrestrial Life in the Stratosphere But Peers Are Skeptical: Scientific American