There's an interesting article over at ClickZ concerning Google's inability to accept ads posted through 3rd party ad servers. Larger brands and agencies want to centralize the administration and reporting of their campaigns, and today Google makes this virtually impossible.

It would seem that the increasing attention on 'Quality Score' from both Google and soon Yahoo will also have an impact on the use of paid search as a branding tool. These types of campaigns are far less likely to use strictly verifiable (ie semantically consistent) language in either or both of the ad and the landing page, so one would expect they'd have trouble getting ranked highly and potentially even run for many of the keywords they'd want to target.

It will be interesting to see how that plays out, with the almighty dollars squared off against the pursuit of relevance.