A long while back Mozilla began experimenting with a brand new way of writing extension for the Firefox, and called it JetPack. It was intended to make it easier for developers to create extensions for Firefox, and make the development processes easier for newcomers, faster and more stabe.
Finally the JetPack SDK has emerged as a beta product known simply as the Add-on SDK 1.0b1. As Mozilla claims, this is not a feature complete beta. The Add-on SDK has been through 10 alpha stages as the JetPack SDK, during which the extension API has changed considerably. With this release the API is finalized, however Mozilla will add features and make small non-breaking changes over time.
The Add-on SDK has been designed to ensure that add-ons created using today's SDK will play well with future technologies that Mozilla introduces. For example, Mozilla plans to make Firefox more like Google Chrome, by displaying web content in different processes. Each tab and extension could then work in a separate process just like in Google Chrome.
Already the number of extenions for Firefox is no small amount, and with Mozilla lowering the bar significantly the number of add-ons is sure to explode. Of course as it becomes easier to make addons, the overall quality of addons is bound to go down a little. In any case, the future looks bright for Firefox add-on developers.