Here's my Rule #1 for Project Managers, as looked at from the perspective of a software developer:
Show active interest in your project, and in the people that work on the project.
Okay, I know that seems obvious -- and I'm a little fired up about this right now -- but I've been amazed to work with project managers in the last few years who seem to have more important things to do outside of work than they have to do at work, and by this I only mean during the Monday through Friday, 8-to-5 time frame.
Politely put, as a software developer, designer, or architect, my feeling is usually something like "Dude, this is your project, or our project, not my project." A developer -- or any employee -- should never have to feel that lack of commitment from a project manager (PM). That is insanely demotivating.
As a PM, you have to remember that people work for their managers or their project managers, not for their company. As a concrete example of this, if I go to work for Papa Johns, I don't work for John Schnatter, or the Papa Johns Board of Directors. I work for the person that hired me, and I'm motivated to work -- or not work -- by the person that hired me. If I think you're an honorable and engaged person, hey, we'll kick some ass, but if I think you're mind is somewhere else, my mind is going to be somewhere else too.
If you don't think that's true, just think of all the times you've heard a group of people leave after one key person has left a company. They didn't work for the company, they worked for that person.
Mr. or Ms. Project Manager, you don't have to be my best friend, but I do need to know that you're committed to the team, just like I'm supposed to be.
And if you're not committed, at least fake some commitment and make me wonder if you're on board (instead of easily knowing that your mind is somewhere else). If we're all lucky, maybe we'll get the project finished before everyone else realizes you weren't really there.