Android 2.0 has turn-by-turn directions, however, I do not yet see an API exposed for this in the 2.0 SDK. Are there any documented plans to expose an API for calling into the new turn-by-turn features?
I will be rather surprised if there is an API for this.
Bear in mind that Google licenses much of this data from TeleAtlas. It is one thing for Google to license it for its own use, and that probably was not cheap. It is quite another thing for Google to license it on behalf of arbitrary third-party developers. This is one of the reasons why the Google Maps API for Android terms and conditions states that you cannot:
8.7. use the Service or Content with any products, systems, or applications for or in connection with (a) real time navigation or route guidance based on position input from a sensor (including but not limited to any visual or audible turn-by-turn route guidance); or (b) any systems or functions for automatic or autonomous control of vehicle behavior; or (c) dispatch, fleet management, business asset tracking, or similar enterprise applications (for avoidance of doubt, you are permitted to use the Service to create Maps API Implementations to track people or assets equipped with a sensor, where the tracking of the people or assets is not critical to the core business or service of the application user. For example, you are permitted to use the Maps APIs to create "Friend Finder" applications that allow consumers to track the locations of their friends? mobile devices, but you are not permitted to use the Maps APIs to create "Business Asset Tracking" applications that track or locate business or government users? field sales or field service personnel, vehicles or other assets that are critical (not incidental) to the core business or service of the application user);
I am fairly certain the above clause is there for TeleAtlas' benefit.
Now, if Google amasses enough independent data to do turn-by-turn navigation, then perhaps I can see an API for it, but not until then.