Product placement has been with us for a long time, but I have to think that the marketing folks have to be interested in leveraging HD.
Think about it. We'll be able to see the logo on an actor's shirt, the brand of shoes, logos on the cars they drive, magazines on the table, etc... So, though content providers are slow to adapt, I'd think this a very important tool for getting across branding in an environment where folks are doing their best to ignore comercials.
Short term though, its going to be hardware manufacturers of both consumer and comercial HD display, reception and transmission devices.