Here is an extremely cool interactive map that shows the single male/female ratio and lets you use a slider to adjust for age. It is based on 2006 census data.
Playing with the slider seems to reveal that at the younger end of the scale men outnumber women, but as the age goes up, so does the number of single women.
In almost any scenario, however, the ratio is very close to 50/50.
Here are some examples where the ages are relatively close, which would mirror a dating situation where people tend to date others close to their own age:
Age 25-34: 1030 men for every 1000 women
Age 35-44: 1004 women for every 1000 men (practically dead even)
Age 45-54: 1039 women for every 1000 men
For men seeking women over 40, the men have a slight advantage. The switchover from extra men to extra women starts at 35-39 for most big East Coast cities, but doesn't hit New York until 40-44. New York seems to have more single women in their 40s and 50s than other places.
This map uses statistics for the whole metro area, including all of the suburbs. The ratios for specific boroughs and counties within the metro are likely different. However, if one assumes that Manhattan is a place with more singles in general, and the suburbs have more marrieds in general, there is no reason to assume that the ratios would be skewed.
Statistical footnotes: Part of the reason for younger men outnumber younger women is the fact that women tend to marry a few years younger than men. This is true almost everywhere. The older end of the scale (54+) skews toward females everywhere simply because men die younger, so there are more widows than widowers.