Jetpack: building Firefox plugin with Javascript (and jQuery)

I discovered a couple of days ago a new open source project from Mozilla labs: Jetpack.
It’s an “API set” which allows to build Firefox’s plugins by using Javascript, HTML (including new HTML 5 tags: “video” and “audio“) and CSS (oh yes, in a single word Ajax).
Jetpack is still in an early development phase and released as 0.1 version.
Here you can find the (really brief) api documentation and here some examples.
I would like to try it in the future