As many have had to deal with, Commonwealth Ventures is doing construction on 30 Channel Center St. and has very loud machinery that they've been operating until past 7 PM at night. They're planning on doing it again this evening and also tomorrow (Saturday). I've called Inspectional Services and the Mayor Menino's office to try to figure out if they were granted a permit and why; normal construction hours in Boston are until 6pm, Monday-Friday.
I'll keep the list updated as I learn more. You can also call Inspectional Services yourself and let them know your concerns at: 617.635.1010.
UPDATE: I spoke with Commonwealth Ventures. The noise is from dust collectors for the sandblasting they're doing and is going to continue through Christmas and probably until New Years. They had intentionally set their hours from 9 AM to 7 PM (instead of the normal 7am to 5pm) to not bother early risers. They're trying to finish the project by Christmas and weren't willing to curb their hours at this point. They did agree to make sure that the equipment was all completely off before 7 PM and in the future look for ways to put equipment facing the Gillette plant rather than residential buildings (they claimed in this case, the duct collectors couldn't reach the doorway from A St.).
UPDATE: I wasn't home after 7 PM Friday and Saturday, but have heard that they worked really late. If you were around and can either confirm or refute this, please email me: email@example.com. Commonwealth Ventures has many more permits they'll need and the city does listen when developers violate them.
UPDATE (1/2): The inspector from the city responsible for that site called me this afternoon. He said they were granted a permit to work off-hours as it was for work inside the building and they're usually granted automatically for work indoors. I told him while the work was in doors, the noise was very much outdoors. Clearly, Commonwealth Ventures was working the system. He agreed to speak with the foreman and watch them more carefully in the future.