What'll be interesting is that once 2010 becomes referred to as 'twenty ten', will 2000-2009 by retrospectively referred to as 'twenty hundred', 'twenty-oh-one' etc? And it what point does it become acceptable to refer to a year by just the last two digits in speech?
So does that mean we're currently on T7?
Surely we're on C21/7? Obviously, you need to be aware of which century we're in, it would be confusing to refer to the year as a number in the 2000s when we're in the 21st century, so 2000 is abbrieviated as C21. From then on, each extra year beyond 2000 is noted by a slash followed by the number of years past it.
It just makes sense!