Where product management guides idea to product, product marketing guides product to market—that is, getting those products into the hands of buyers (and their sellers).
Just as product management investigates friction for users, product marketing identifies friction for buyers.
As product management is to development, product marketing is to marketing. That is, product marketing finds go-to-market problems and works with marketing teams to solve those problems.
Here’s an example: in doing win/loss analysis, the product marketing person hears that many people (not just one) are reluctant to buy from you because you’re not as well-known as other vendors. The product marketing person shares that issue with marketing who determines that your team should embark on a thought leadership campaign. That means writing key articles about the industry (NOT Your product) and building a reputation for thoughtful, non-salesy content. Or perhaps product marketing learns that many prospects are confused about some technical underpinnings of your product (such as cloud vendor or security). Rather than trying to train the sales team, marketing creates a video of your CTO explaining why the technical choices that were made.
As for common programs (such as blog, community, podcast, etc), you must begin with two things: who are the personas you are trying to help, and what problems can you solve for them? When I started blogging in 2000, my initial articles were inspired by my emails—topics or concepts that were misunderstood. In my case, I’ve written about roles and how product managers can work better with developers. My BUYER is the VP of Product, but my USER is the product manager and product marketing manager.
Product marketing helps reduce friction for buyers (how do we make it easier to buy?) and for sellers (how do we make it easier to sell?) Product marketing finds the issue (problem), and marketing creates the campaign (solution).
As with all things product, begin with the persona and the problem, and then work with solutions teams (in marketing and development) to design solutions to those problems.