While this won't be news to those who follow Census developments closely, it is a nice summary of some of the important deficiencies in the American Community Survey:

• 2005 American Community Survey by Roger Owen Green, NYS SBDC Research Network (November 21, 2006)

Writing for the New York State Small Business Development Center (NYS SBDC) Green notes that:

...because of previous cuts in the Congressional funding, the 2005 ACS does not capture data from group quarters, which include prisons, college dormitories, and nursing homes.

One thing this means is that in geographic areas where there is a large group quarters population, comparisons of figures from ACS to Census 2000 may be inaccurate or misleading. As Green says, "...politicians and the media have glommed onto these new statistics, making assertions about populations that the methodology does not support."