I've yet to hear anyone to refer to twenty ten. The year 2000 kind of changed everyone from the "nineteen xx" stuff to using "two thousand xx". That was a significant change going from 1999 to 2000. There's nothing significant about going from 2009 to 2010 like it was back then at the turn of the century (before you all jump in, I know the turn of the century was actually 2001....)
Back in 1901 no-one said "the year is one-thousand-nine-hundred-and-one" They probably said, nineteen hundred and one.. Less syllables you see.
When we refer to 1901 we usually say nineteen o-one or nineteen hundred and one.
Now we come to 2000. or Two thousand, less syllables than Twenty hundred.
Two thousand and one,
Two thousand and two,
Two thousand and three,
Two thousand and nine.... all have very few syllables, but of course twenty-o-nine has less syllables? The thing is, thousand is pronounced very fast so never got beaten by the word twenty. Also it can be expressed as Two-thousand-nine without the and making it even shorter. ALSO, when you say the -o- "oh" part, it breaks up the phrase and makes it "sound" longer.
Now Two thousand andTEN, the same amount of syllables as Two thousand andnine (2009). So my guess is people will keep the same thing going. In fact I do hear people use both two-thousand-and-ten (or two-thousand-ten) AND twenty-ten when talking about 2010. Less have been saying twenty-ten though. It's not so common but still I hear it.
My guess is the pronounciation twenty-blah-blah won't catch on in mass until we are at 2011 and it's faster to say twenty-eleven than saying two-thousand-and-eleven.
I think people don't say Y2K-ten because the phrase "Y2K" sounds very "nineties" and people don't want to sound old fashioned. Nor 2K-ten because a lot of the time people use the "K" suffix when talking about annual salaries or they don't want to sound like a propellor-head talking in megabytes in tha Iraq, everywhere like such as....
When referring to events and things, definitely 'twenty-ten'. Otherwise, I still find it more comfortable to say 'two thousand and ten', as that's what I've been doing for the previous decade. Give it a little while and I'll probably be using 'twenty-ten', 'twenty-eleven' and so on.