Android Developers Blog: Integrating Application with Intents — a nice writeup about really, seriously underappreciated Android feature, Intents. Somehow it's reminiscient of the revolutionary Magic Ink proposal, albeit on a push, not pull basis.
Having said that, I can't shake the feeling that making up URI schemes is not cool. Especially when they're made up to go with an Intent action which is actually redundant with the scheme. URI should point to a location, not embody action; actions should go in the action field (hey, action–action, ya see? almost like it was designed for that!).