When the Church Fathers created the Anno Domini dating system many centuries ago, there never was a Year Zero. The very first year of the Christian calendar was 'Year 1', so obviously all decades thereafter ended at 'Year 10', not 'Year 9'. Simples!
Most of us don't buy into that religious guff and so the simply numerical form of the year number is what matters, and so today is the start of that decade of dates in which the four digit year number is of the form 201x.
HNY/HND to all.
I am going for two thousand and ten. I might even throw in a "Year of Our Lord" beforehand, just to sound even more formal, and appease the religious minded that I might happen across. :)