In reply to TheDrunkenBakers:
If it was indeed shot down (and that seems far from settled as far as I can see), then I can see no political or military advantage for the pro Russian separatist to purposefully shoot down a civilian airliner, so you could surmise that it is essentially a terrible mistake.
They have been targeting Ukraine military jets and transport planes in recent months, and have shot down 4 or 5 I believe, although none at anything like the altitude of the airliner. So they have 'form', so to speak, but obviously they would need some fairly sophisticated weapons to target something at 32,000ft. Perhaps if such weapons have been supplied to the Separatists by the Russians, its possible to believe these operating them might not be as well trained as they might otherwise be, and targeted the airliner by mistake?
Listening to a piece on the radio this morning, apparently there has been controls in place to prevent any civilian airliners from flying below 32,000ft across this bit of the Ukraine for some time, but flights do cross the area on a regular basis, so why has this only happened now? And it seems to call into question the wisdom of crossing war zones entirely, when such weapons might be on the ground.