Ask HN: Thoughts on scrum master positions?

What are your thoughts on "Scrum Master" job positions?

I have never held such a position formally, but I have informally. It seems that the Scrum Master performs some of the duties of a manager without actually being a manager. So while you can't hire and fire anyone, you might spend most of your day responding to emails, being in meetings, planning releases, etc.

On the one hand, it seems like a lame duck position where you handle all the day-to-day tedium of management without being able to effect real change in the organization. On the other hand, it also seems like a "management lite" position that could be a stepping stone if you wanted to eventually break into management.

Anyone have experience / insight?