Summary: an anonymous survey with 50 responses indicates that the average salary for full-time, Boston-based Rails developers is $99,646
Several weeks ago I posted to the Boston Ruby Group mailing list asking people how much money they made. I asked people for their annual salary (including bonuses), how they'd rate their Rails skills from 1-10, whether they managed other developers, and whether they were freelancers.
Average salary (non-freelancers): $99,646
Average salary (freelancers): $114,000
Average salary (no management of other devs): $88,340
Average salary (with management of other devs): $113,040
Average self-rating of Rails ability (1-10): 7
Raw data, and the brutally-complicated code I wrote for averaging a handful of numbers lives on github.
Thoughts on the results:
Based on conversations with those familiar with the local market and my own experience, these numbers seem a bit high. I have a hunch there is selection bias at work: perhaps developers that are proud of their salaries are more likely to respond. Additionally, I'd guess there's a tendency for people to exaggerate slightly on these sorts of surveys. Naturally, you should treat these numbers as you would any drawn from an anonymous survey sent to a public mailing list.