Introducing third-party ads on the Google content network

The Google content network now accepts display ads served from qualified third-party vendors. Third-party ad serving has been a longstanding request from top brand AdWords advertisers who use third parties to create and manage their online campaigns. Initially, we will be only accepting third-party ads in English, but we hope to expand to other languages soon.

Making the Google content network more accessible to large brand advertisers also benefits AdSense publishers and end users. Third-party ad serving will introduce a greater variety of advertising into the Google content network, increase the inventory of quality display ads competing to show on AdSense publisher sites, and offer more engaging ads for end users. In the long run, we believe the increased inventory and ad competition will result in increased revenue for many AdSense publishers.

Rest assured that ad quality on the content network will remain one of our highest priorities. Only advertisers with whom we have proven relationships and who've clearly demonstrated commitments to our quality standards may participate in this program. And our policies governing ad content and formatting are unchanged.

How to control third-party ads shown on your site
The same ad management features for Google ads also apply to third-party ads. You can use the Ad Review Center to filter specific placement-targeted ads from appearing on your site. To block contextually-targeted ads from a given advertiser, you can use the Competitive Ad Filter. (The Ad Review Center currently only shows placement-targeted ads, not contextually-targeted ads.)

Optimizing your site to allow third-party ads
To allow third-party ads on your site:

1. Opt into image ads - Currently, third-party ads are only available in image or Flash, so they won't appear in text-only ad units.

2. Enable advertisers to target your AdSense channels - Most advertisers who use third-party ads are brand-conscious. They prefer to specify websites where their ads will appear in order to optimize the targeting and effectiveness of their campaigns.

3. Opt into placement targeting - Placement targeting will allow advertisers to target their ads specifically to your site.

Following these steps will enable your site to accept third-party ads. However, we can't guarantee where or when third-party ads will appear on your site.

Source: http://adsense.blogspot.com/2008/05/introducing-third-party-ads-on-google.html