A new map of the ecoregions of New York is available to use with ArcMap GIS and will soon be available in print. This was a joint effort of the EPA, New York Natural Heritage Program, USGS, NYS DEC, and NRCS. Two of the principal authors are Greg Edinger from the NY Natural Heritage Program and Doug Carlson from NYS DEC.
You can download the files for GIS as a zip file at:
ftp://ftp.epa.gov/wed/ecoregions/ny/
The printed maps will soon be available for $10 at the USGS store at: