Firefox 3 had some big changes (and little changes) that caused some grief for extension developers wanting to update add-ons to the newest version. There were some deep architectural changes (Places bookmarking API), numerous security changes (same-origin on file:// and restricting chrome:// from content), and large UI/Theme changes (URLbar, XP/Vista/Linux/Mac themes). Needless to say, getting lots of new greatness in Firefox 3 (XULRunner 1.9) came at a high maintenance/refactor cost to extension developers.
The good news is you made it! Overall, I think Mozilla did a good job keeping developers updated on changes and, along with a great developer community, provided lots of help to developers who were having trouble updating extensions.
So, you might have heard that Firefox 3.1 is coming out soon, probably before the end of the year. Firefox 3.1 alphas could start showing up in less than 2 months. If you have been reading some other posts on Planet Mozilla or watching some of the checkins landing in the source tree, you might be aware that Firefox 3.1 will add some serious, ass-kicking features. Many of these features are web-content facing and are based on web specifications.
Will all of these serious, ass-kicking features mean that updating extensions will be a major pain-in-the-ass, again?! No! There appear to be no plans to make extensions developer lives miserable. The new features (did I mention they kick-ass?) are not being added in a disruptive manner. Most of them layer onto existing features and technologies.
Just to be clear: Firefox 3.1 will not require a major update for add-ons. In fact, I’d go out on a limb and say updating to Firefox 3.1 will be easy. We’ll make sure the are no surprises along the way.