Yesterday Russia's deputy prime minister explicitly threatened to veto the Ahtisaari plan for limited independence for Kosovo. Thus far the Russians have been fairly silent on the Big-V; they haven't threatened to use their Security Council veto.
My guess is that US-Russian negotiations on the proposed US missile shield are not going well and that the Russians are upping the ante a little bit. According to the EUObserver,
"A decision based on Martti Ahtisaari's draft will not get through the UN security council," Russia's deputy prime minister Vladimir Titov confirmed on Tuesday (24 April), Russian newswires Interfax and Ria Novosti report.
"The threat of a veto should stimulate the search for mutually acceptable options," he added, following months of hint-dropping by Russian diplomats that they would use the ultimate UN sanction.
There hasn't been much linkage between these two issues in the media, but I do not doubt that the missile shield and Russia's acquiescence to the Ahtisaari plan are closely linked (this article almost links them). Make no mistake, while the Russians are often touted as the Serb's big-brother, the Russians are for the Russians. They will happily trade off any of the Balkan states to advance their own foreign policy objectives.
Of course, the Russians aren't the only ones to use the Balkan states for their own ends; all the world powers have done this. That's why in the Albanian mental DNA there are only two categories of foreigner: the Eastern ones who have invaded and occupied them, and the Western ones who have betrayed them. Thus far the US has remained a curious third category.