Time is not a natural thing. It's man-made. And usually, we screw it up. GMT (Greenwich Mean Time) is the world time. It represents the date line time zone beginning 1880, and is also called UT and UTC. To call it UTC is not perfectly correct, but widely accepted. Everyone should know their time zone, or offset, which is GMT+-x. For example New York is GMT-5. San Francisco is GMT-8. Europe (EU) is GMT+1 and Japan is GMT+9.
While this is no solution for having one fixed time for every country, it's the best shot until metric time is accepted (if ever). You will discover what that means at 1.1.2011 at 0:00. You probably celebrated several hours late, and some other will celebrate 23 hours late.
I think we really need to use the world time, especially in the net. So in New York you celebrate the new year at 1.1.2011, 05:00 GMT. Oh and yeah, there is a reason why the Army uses UTC (Zulu time) with 24hrs format, too. AM/PM is so ancient, it should have been buried 50 years ago.