Wikipedia wrote...
Among experts and the general public, there is a debate as to how specific years of the 21st century should be pronounced in English. Although the majority of English-speakers say "two thousand X" for years of the current decade, in theory this could mean any year up to 2999.
One article suggests that since, for example, former years such as 1805 and 1905 were commonly pronounced as "eighteen oh-five" and "nineteen oh-five", the year 2005 should naturally be pronounced as "twenty oh-five", and that majority usage of "two thousand (and) X" is a result of influences from the Y2K hype, as well as the way "2001" was pronounced in the influential 1968 film, 2001: A Space Odyssey.
In addition, the Vancouver Olympics, taking place in 2010, are being officially referred to by Vancouver 2010 as "the twenty-ten Olympics". The London Olympic Games and Paralympic Games Act 2006 has restricted the commercial use of the terms "two thousand and twelve" and "twenty twelve", to protect the London 2012 Olympics.
According to a recent press release, David Crystal, author of the Cambridge Encyclopedia of the English Language, has predicted that the change of pronunciation to "twenty X" will occur in 2011, as "twenty eleven", explaining that the way people pronounce years depends on rhythm, rather than logic. Crystal claims that the rhythm or "flow" of "two thousand and ten", beats that of "twenty ten", but the flow of "twenty eleven" beats "two thousand and eleven". Alternatively, Ian Brookes, editor-in-chief of Chambers Dictionary, suggests the change will occur in 2013 (as 2012 is often referred to as "two thousand and twelve").