Kind of fluffy. I always worry about descriptions of roles that seem more about selling the role than about the stuff the role owns; you worry about aspirants getting the words "product manager" on their b-card and then not doing anything, like what happened with "architects".

Product managers own most, often all, of:

* Customer outreach: The PM is ostensibly the one with routine scheduled calls to all the clients to collect feedback.

* Feature/function/benefit: the PM usually co-owns the roadmap with engineering, and the split is usually that the PM mostly owns the ordering of things on the roadmap, engineering owns the time estimates, PM describes the feature and the business benefits it solves --- both to customers and, when the job is done right, to engineering.

* Pricing and packaging (in a startup, the PM is probably going to own pricing; in a mature company, nobody is going to trust the PM to own the most important business decision about the product).

* Competitive analysis: the PM is who you blame if you get blindsided by a customer dropping your product for a competing offering.

In mature companies the PM role often ends here and is picked up on the other side by Marcom, who is in turn going to outsource the copywriting and design of white papers and sales material and websites. In a startup, you'd expect the PM is going to own the marcom stuff too.

For a startup, most of what Joel writes on Joel on Software, especially the earlier posts, is a record of the job of a small company product manager.