Jetpack 0.8 helps automate web site mashups
Another new API provides access to browser windows and tabs. Event handlers can be registered for both object types for the events
close, and tabs also send
paint events. The Panel and Page Worker modules also now behave more like Web Worker for HTML 5. One known issues it that some Jetpack tests fail with the nightly releases of Firefox 4 which is currently in development.
Jetpack based extensions allow for developers and users to extend Firefox without using the old XUL extension system which is hard to maintain. Jetpack extensions can, for example, can be installed, reloaded or removed without restarting the browser.
Updates on Jetpack's progress have now moved to the Mozilla Add-ons blog as the project has graduated from Mozilla Labs to become a full Mozilla project.