This rumour has been doing the rounds for a long time, and is therefore one of the most plausible, that Fallout 4 will take place primarily in Boston. An anonymous Reddit user - a reliable source if there ever was one - posted last August that Bethesda were location scouting the Massachusetts Institute of Technology, and given that The Commonwealth basically doubles for Massachusetts in the Fallout universe (and even has the Institute), that would absolutely make sense.
Bethesda hasn't commented on the rumour as they never tend to, and that really has only sparked even more speculation that it might be true. Of course, the source is dubious at best, but it makes a Hell of a lot of sense given what we've seen in Fallout 3.
Frequently sleep-deprived film addict and video game obsessive who spends more time than is healthy in darkened London screening rooms. Follow his twitter on @ShaunMunroFilm or e-mail him at shaneo632 [at] gmail.com.