The Census Bureau has just released the 2007 American Community Survey, an annual investigation of the demographic and socioeconomic characteristics of states, counties, and municipalities with populations exceeding 65,000 people. Over 3,000,000 households were surveyed for this survey, giving government planners more current data than those supplied by the decennial census(which is required by the Constitution, btw). So, if you come from a state, county, or municipality which has more than 65,000 people, you can get recent population information right here. And since Jersey City fits the above criterion, its figures can be accessed here.