Short Version: How does the new Calypso application (powering Wordpress.com) communicate with a privately hosted Wordpress blog via the Jetpack plugin? i.e. Does Jetpack expose an API on my Wordpress hosting site? Or is there other black magic going on.
Long Version: Calypso is a new javascript based application for managing blogs at the commercial hosting site Wordpress.com. You can't use Calypso to directly manage blogs hosted privately with a copy of the open source Wordpress application.
However, there's a plugin for Wordpress called Jetpack. It's my understanding that, with the release of Calypso, it's now possible to manage content in your privately/personally hosted Wordpress blogs via the Wordpress.com/Calypso application if you have Jetpack installed locally.
What I want to know is: How does Jetpack do this? I assume Jetpack exposes some sort of API on my private blog. Is that true? Or is there some other black magic going on?
Does Wordpress.com/Calypso just sync regularly with my private blog? Or are the updates in real time?
Context: I'm trying to understand the technical implicates of opening up my private blog to Calypso to ensure that features I program into wordpress plugins will play nice with whatever Jetpack is doing. i.e. What does the Calypso->Jetpack->PHP Wordpress Application technical architecture look like?
There's multiple StackExchange sites I could ask this on -- but the Wordpress StackExchange seems focused on practical day-to-day use of Wordpress and not the technical implementation. Since I'm a programmer, that makes Stack Overflow the next best bet.