Mark, John: ethnic questions in the Ukraine are immensely complex and are far too big a topic for one brief post, but I think it’s worth saying that, whatever some Russians are saying, over seventy percent of Ukraine’s population describe themselves as ‘ethnic Ukrainian’ (although high rates of intermarriage between Russians and Ukrainians make the determination of ethnicity even less reliable than is usually the case). It’s also important to note that the idea that Ukrainian culture (as we now understand it) is solely, or even primarily, the product of those parts of Western Ukraine/Eastern Poland annexed in 1939 is quite wrong. There was clearly a distinct sense of Ukrainian identity in the pre-war Soviet Ukraine – and that was why Stalin spent so much time trying to exterminate it. As for identifying the the difference between Ukrainians and Russians, you can possibly draw a very rough comparison with the difference between the contemporary English, the Scots and the Welsh – it’s difficult to define, but you know it when you see it.
It’s also not quite right to draw too sharp a distinction between Georgia and the situation in the Ukraine today. Georgia is, in fact, very far from being an ethnically homogenous state, but its rose revolution began in the Georgian heartland. In fact, in a possibly ominous precedent, it has yet to be extended to the whole country.
The key point is that the decision to preserve the republican boundaries of the old USSR (which were often drawn up in a way designed to stifle local nationalisms) has meant that there are very few clearcut ethnic boundaries anywhere within that vast territory.