Where I worked before I went back into academia, the title "Project Manager" referred to someone whose main job was running interference between engineers and upper management. She was always coming up with answers to questions about how long things would take, etc. so I wouldn't have to and prompting me for various answers that upper management actually cares about. Definitely helped me get things done.
That place was emphatically not Silicon Valley, though, so it makes perfect sense to me that the two positions share little more than a title and not coding.
I'd just like to point out to both you and the parent mmaunder said Program manager/product manager, not Project Manager. But if he means a PM, then fair enough.
Anyone who thinks a good PM isn't worth their weight in gold is seriously la-la and probably hasn't worked with one.
That place was emphatically not Silicon Valley, though, so it makes perfect sense to me that the two positions share little more than a title and not coding.