I've been thinking about this for a while. Some applications, such as Amarok, use Plasma and specially designated Plasmoids to create the Context View. This is done by embedding a Plasma container inside of an application, I'd imagine.

Is there somewhere that I can find some documentation on how to specifically do this? The idea of Plasma-based controls on certain applications is a promising concept to me, and I'd love to start tinkering around with it more!

There is not anything special about embedding plasma in applications.

Just create a QGraphicsView and show Plasma::Corona (inherits QGraphicsScene) in it. Then, add applets to Corona.

For further info, just read the API docs about those classes, and that's that