The longer I live, the more I internalize it: We succeed or fail to a large extent because of our ability to establish and sustain good relationships. Yes, you need a strategy and need to be smart enough, but PMs need to be leaders. If no one is following you, you're not a leader!
Think about your own career ups and downs. How many of failures are you blaming on others? And how many successes do you chalk up to your own brilliance? I suggest that you take a look inward and you'll find the seeds of many of the problems you experience in the outside world.
My friend and colleague Michael Papanek has just launched a new blog covering topics that will help you in your career as a product manager. Michael specializes in strategies, skills and tools to implement change. Michael has taught me a ton about collaboration, leadership, and personal and organizational change. If you'd like a sample of his thinking, here are some articles to get you started:
Finally, I interviewed Michael a few weeks ago on what he calls the "Resilient Relationship". You can hear our discussion here.
Every PM should be thinking about leadership and organizational issues!