On this page for the Division of Public Records from the Secretary of the Commonweatlh's web site you can find a document called "A Guide to the Public Records Law" as well as some other related documents and links.
This presentation prepared by Neil MacGaffey at MassGIS provides a short overview of the essential requirements and provisions, including specific exemptions, of the public records law as it pertains to GIS data; many of the slides reference specific pages in the document mentioned above "A Guide to the Public Records Law". (187 kb; in PDF format - requires the free Adobe Acrobat Reader software or plug-in)
In 1996, Mary E. Schwind, then Acting Supervisor of Public Records, Commonwealth of Massachusetts, wrote a letter to Daniel M. Funk, City Solicitor for the City of Newton. In this letter, Ms. Schwind responds to some specific questions concerning interpretation of public records law as it pertains to GIS databases.