I have been studying the MassGIS page in the wiki as well as the
MassGIS website. The MassGIS website has large amounts of high-quality
data that is in the public domain. Some of it has already been imported.
This includes a high-quality streets layer and a somewhat lower quality open-spaces layer.

There is a lot more that I would love to see imported, such as town borders. I am willing to work on this, but I have run into some problems:

1) The documentation for the import tools is in disarray. It fails to identify the current best practices. So far I have been able to generate an OSM file which I can load into JOSM. I have not uploaded it because I have not yet figured out how to tag it properly.

2) The MassGIS import project appears to have gone dormant about a year ago. Identifying the participants has proved difficult.

I have been labouriously pieces together the necessary information and updating the wiki.