While I can see how such a system may automate some of the manual work currently done by the radio sales staff, ad agencies, and advertisers, I'm not sure how the feedback mechanisms of AdWords/AdSense will be employed. Unlike the Internet, there is limited feedback in radio. A few people call in; some interact via email and/or the station's web sites; some also interact via cell phones, but for the most part, it's a passive medium. In particular, most radio listening (that is highly valuable to advertisers) is done in cars during rush hours, where people are driving, for the most part. Also, AdSense in particular matches ads to web site contents, so it's not clear to me how that will be leveraged. (For example, if the talk host starts discussing Dubya's latest escapades, will it be followed by a Commander-in-Chief spot?)
Measuring audience listenership/response in radio has it's own can of worms. Lots of people don't trust Arbitron because they feel the surveys don't go to a statistically valid sample of the population, are likely to be ignored by people who are too busy to fill out diaries, and so forth. But any "online" measurement will have its share of problems. Unless ...
The cost savings of Google automation made online advertising competitive with print and broadcast advertising, so perhaps the Google method of automation will enable radio advertising to be more efficient and profitable for all parties. Also, since Google is starting out with difficult to sell spots late night radio, the pressure won't be on them to immediately achieve results. And since they're been so successful (at least financially) with online advertising, it gives them a "safety net" to iron out the problems. So perhaps they will be successful.
There is a dark side to this, however. The individuals who currently do the buying and selling of ads may be in for some displacement if Google-dMarc really catches on. Some people are skeptical about this, saying that automation can't replace the personal relationships that ad buyers and sellers have built up over the years. But radio has to find ways to remain profitable in this era of consolidation and cost-cutting, which could put those people's jobs at risk if automated advertising allows stations to reduce costs.