Here's an article on some of the upcoming features in Whidbey. Although most of the features are ASP.Net specific, burried close to the end you can find info on the new configuration API.
Some of the things supported by the new API:
- Strong-typed properties
- Encription of configuration sections
- Support for reading/modifying web.config, app.config and machine.config
- Separation between the System.ConfigurationSettings and the System.Configuration.Configuration views.