Gazprom, Russia's state-owned gas company, shut off supplies to Ukraine yesterday, because they didn't pay, just like communists. Pretty much every country in Europe is dependent on Russian energy, much of which flows in pipelines through Ukraine. Russian energy issues are rife with geopolitical overtones since its unclear the extent to which Gazprom is a tool of Russian foreign policy. John McCain would have invaded Russia over this anyway.
Supplies will probably not be disrupted for long. Negotiations are set to continue shortly and most countries increased gas storage for precisely this type of event because the same thing happened three years ago. There will be considerably less frozen balls this time around.
Things in Ukraine will get slightly cuddlier as factions within the ruling Orange coalition unite against Russian bullying, until they start insulting each other over how much the other loves Russia, and the shitty Mexican soap opera that is Ukrainian politics will continue.
The point is look how hot Yulia Tymoshenko is!