Firefox's Jetpack SDK boosted to 0.4
The new version includes four new APIs and a pair of new features. The page-worker API allows for add-ons to create their own invisible frame to load and access web pages while the new widget API provides a consistent way for add-ons to show themselves for user interaction. simple-storage is a new API for saving data locally and between application restarts and private-browsing lets add-ons detect if the user is using Firefox's private browsing features. These new APIs are complemented by the two new features, restart-less add-ons, which allow add-ons to be installed into the latest nightly testing builds of Firefox and an "Unforgeable ID" for add-ons cryptographically created by the SDK, which will allow Firefox to verify updates came from the same source as the original version.
A detailed change log and the SDK are available from the Jetpack 0.4 release notes wiki page.