San Francisco Chronicle and San Jose Mercury News First Customers to Go Live

In simple words APT from Yahoo! is a digital advertising solution. It helps to streamline the process of planning, buying and optimizing display advertising.
It is designed to buy/sell ads online in a simple way, while connecting all the market players -- publishers, advertisers, agencies, networks, partners and developers
APT is a single platform for connected digital advertising, including ad serving, ad network and ad exchange. It is designed to streamline advertisers' ad-buying process for multiple accounts across multiple publishers, and enable creative testing and campaign optimization. It also helps advertisers to easily identify audiences through geographic, demographic and interest-based targeting.

Key advantages of APT from Yahoo!

The ability to connect to new business partners for cross-selling
Providing ad selection and inventory management tools to match relevant ads to marketers' target audience
Publishers can create their own private network.

Some of the initial capabilities featured in the new platform include

Guaranteed cross-selling with pre-defined selling rules
Audience targeting techniques based upon behavior and geography
Filters for better controls around creative
Flexible and powerful APIs
Federated ad call to support multiple ad formats

Yahoo! will start to make the platform available to other parties including advertisers, publishers, networks and agencies in 2009.
Additional information on APT is available at http://apt.yahoo.com.