[ilovecaching]

The role of a project manager is to have someone who can represent the user. The project manager should be talking to users, soliciting product feedback, getting bugs filed, and feeding this to the team.

The role of a manager is to manage the people on the team. That means helping them grow their careers, help them switch teams if they find something that would be a better fit, promote the teams work, unblock people, give feedback on how team members are communicating, manage meetings and fill in for team members so they can spend more time coding that sitting in meetings.

Basically a people manager is like a boxing manager. He gets the champ into shape, puts him in to the ring, and cheers him on. When the champs not fighting he makes sure the champ can focus 100% on training.

[ianbicking]

I think you mean "proDUCT manager" – a project manager usually focuses on schedule, balance of work, bottlenecks, and maintaining (but not defining) priorities.

It's pretty common for an engineering manager to do project management, and to some degree it's necessary: people management and priority management are closely related.