Do a search on product management vs. product marketing and there is no shortage of articles on the subject.
Avoid a “Trap” in the Priorities of Product Management vs. Product Marketing uses the inside-ouside definitions to differentiate management and marketing then goes on to make the point that marketing should focus on only a couple of messages.
Bruce McCarthy in his user driven blog makes the case for differentiating the roles of manager and marketer and also cautions about product managers becoming too involved in sales support so that they don’t effectively provide product direction.
Of course these two disciplines should be complementary, so the dynamics of their definition and interaction are important success factors for new product introduction.
The upcoming (March 11) Zone5 event Product Branding From the Inside Out – And Back in Again promises a lively discussion on how product management (inside of the brand) and product marketing (the outside of the brand) can be successfully combined.