We want to assure everyone in our community that XUL-based add-ons are not going anywhere in the foreseeable future. Mozilla is committed to keeping Firefox the most customizable browser, and add-ons are here to stay. Without our add-ons community, Firefox would not be the most extended browser in existence, and we owe them an enormous debt of gratitude for getting us to where we are today.
Project Jetpack explores an additional way of creating add-ons for Firefox, and no plans have been made for it to completely replace XUL-based add-ons. If you’re interested in learning more about Jetpack or helping to shape its future, you can read more on the Jetpack blog.
We hope this clears up any confusion, and look forward to 2010 as the best year for Firefox add-ons yet.
– the Firefox Add-ons team