They cut off the country's Gas Supply a couple of days ago (due to wanting to quadriple the price the Ukraine pays Russia for its gas - a hike that Ukraine claimed was politically motivated due to the countrys move away from Russia and closer to the West - which looking at the stats involved I'd say was almost certainly partially correct). Now Russia is accusing the Ukraine of stealing $25 million of gas that was en route to EU countries. It's a tricky situation as the pipes run through the Ukraine (which was one of the reasons they were getting cheaper gas from Russia).
Ukraine "Stealing Europe's Gas" (BBC News Online; Monday 2nd January 2006)
Energy And The New World Power Play (BBC News Online; Sunday 1st January 2006)
Putin Admits Ukraine Gas "Crisis" (BBC News Online; Thursday 29th December 2005)
Loads of other links in the respective articles...