A 400% increase in price, porbably motivated by political factors rather than financial necessity.
Some EU states (Latvia etc) still pay less than a third of the new price for Ukraine.
European governments are having serious concerns about Russias current and future energy policies and Russia's ability to remain a fair partner, despite Putin's assurance to be just that. It's also widely seen as Russia flexing its muscles and indicating its regional importance - some even see it as the first action taken in an attempt regain its former status as a world superpower.
Stocks in Danish alternative energy companies have seen a boost.
As with Russian things in general - very stubborn and either very brave or very stupid move by Putin. He's a smart dude, though and I gather he has judged the political landscape accurately.
Essentially, he's said "Dudes. We. Got. Power. Don't forget that".