The patch released on 15 December 2010 change some values, the values for non-standard map sizes are not updated
The mouseover for your own score helpfully shows from which categories how much of your score originates.
I've experimented a bit and my preliminary composition of the score is the following:
Duel Tiny Small Standard Large
City 21 13 11 10 6
Population 6 4 3.5 4 ~1.5
Land 2.11 1.35 1.15 1 (water tiles don't count, the city hex does)
Technology 4 4 4 4 4
Wonder 40 40 40 25 40
Future Tech ? ? ? ? ?
These results are from the start of a game, I assume they don't change but I can't be sure yet. It seems some things count for fractions of a point, so the numbers here may be rounded. The numbers also seem to be always rounded down, not to the nearest number.
Units and Gold do not seem to have any effect on the score.
Wonders count for a lot at 40 point per wonder. But also new cities (at standard map size) result in 19 points (10 for the city, 3 for 1 population and 6 for the land). Technology seems to be rated pretty low at 4 points, you have to research 5 technologies to get more points than one new city.