I’m using various social networking tools to help support and grow my business. Facebook, Twitter, etc. As a user as well as a business owner, I don’t think the social networking platforms are useful as advertising venues. Rather, they provide a great mechanism to keep in touch with my clients and peers. I see what they’re up to, they know what I’m doing.

For the most part, any ads that I see I ignore. They rarely fit my interests, so they are definitely failing on #1-Drive “vertical”, highly segmented participation, which drives context for Display Ads. They do try, but either they haven’t gathered enough information about me or they don’t know how to use the information they have. That is the key, I think. They either have to figure out the right questions to ask of me or how to best use the data they have.
As for your question, Jim, about reasons it can’t be done: no reason it can’t, but someone will have to work at it. Again, marketing needs to drive the technology.