If you are interested in using Silverlight for advertising, check out the Silverlight Ad Publishing and Serving Guide. This paper describes the Silverlight features that are most relevant to people who create, serve, and track advertisements. For example, the paper describes:

• Cross-domain ad hosting.
• Ingesting ads into a creative management system (including Deep Zoom ads).
• Synchronizing multiple Silverlight ads on a single Web page.
• Implementing graceful downgrading for users who do not have Silverlight installed.

The Silverlight features described in this paper are covered in the official documentation, but the emphasis on the advertising scenario provides some practical insights for those of you in the marketing biz.