I'm inclined to say 'two thousand ten', but I think that is because I vividly remember (the last decade of) the twentieth century, and this young century STILL has a bit of a new, even alien, feel to it for me. But I suppose youngsters who will have been born in this century will be more comfortable with calling the years 'twenty-something'.
I call this decade the 'two thousands'... Remember, what most of us call the 'nineties', 'eighties', 'seventies', is simply short for 1990s, -80s, -70s. Some years or decades from now, the '19' will be slapped back on those decades when referring to them, to distinguish them from the upcoming 2070s, 2080s, and 2090s, which will THEN be the 'seventies', 'eighties', etc.
I always think it's fun to point out that the second decade of this century won't start until January 1st 2011, because there is no year 0. However, the '2010s' themselves, of course, start with and include the last year of THIS decade.
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clarity of thought before rashness of action