Mark blogged about the new Firefox -app switch, which I think is a pretty interesting thing. Of course, it’s not a substitute for XULRunner, which gives the application developer complete control over important things like the update cycle and process, and it’s definitely not something that we’re recommending people use without a lot of careful study.
This is something that we’ve been asked to provide for quite some time, and even with the tight coupling to Firefox in versioning and launch syntax I think it’s going to be a valuable addition to the repertoire. Here’s how I now see the platform spectrum for our technology:
Web applications. If you can do it here, you should. We’re working with other browser developers to develop and standardize new web-platform capabilities all the time, because being able to put your app in this bucket brings a ridiculously large number of benefits for users and developers both. With webrunner you’ll have a way to give users an optional desktop-launch experience that they may be more comfortable with, even.
Firefox extensions. There are thousands of them that have been able to build great experiences (and, in some cases, great businesses) with products that are tied to the Firefox maintenance-update rhythm, and we’re seeing more great stuff all the time.
Firefox “-app” apps. This is a nice little hybrid where you are still coupled to the Firefox update cycle and so forth, but get more isolation from the browser process and end-to-end control over the UI. As Mr. Finkle said, this is a sharp tool with its handle loosely attached, so please use care when using it. If extensions aren’t suitable for your project because of the update cycle model, then this very much won’t be either. For prototyping, or some extension-like uses, it’ll be killer, though. (I like that the apps are started with “firefox -app”, because it’s another hint that the thing you’re doing is dependent on Firefox, and that changes to Firefox could hurt it. I think it would be more confusing to have it be called “apprunner”, f.e.)
XULRunner apps. I need say little more on this topic; Joost and Songbird and Komodo and Miro and…yeah.
By no means do we expect, recommend or condone XULRunner-grade apps being moved to this model without extreme care, but a lot of people building such apps, especially smaller ones, have been asking for a way to piggyback off Firefox’s awesome update story while still having their own top-level chrome.