Mozilla Prism, I run to thee...
I'm having trouble fighting feelings for Mozilla Prism.
At first, it seems like a fairly stupid concept. For one, I already run a browser — why do I need a dedicated XULRunner task that can't switch URIs? [*] The obvious alternative is to just open a new browser window and run my web apps in there. I can think of a few other non-advantages (not to be confused with disadvantages):
Firefox remembers the last tabs that you had open from multiple windows, which minimizes the benefit you get from launching a single web app.
Different Firefox windows don't cluster their behaviors in the X server (e.g. I can make a single Firefox window appear on all desktops but no other Firefox windows).
There exist Firefox extensions that allow you to freeze individual tabs at particular URIs (e.g. you can create a dedicated GMail tab with the Tab Mix Plus extension).
The only real advantage that I can come up with is the beautiful separation of concerns inherent in a necessarily separate Mozilla Prism instance. Sure, extensions allow me similar behavior; however, the locked tabs (or [insert similar solution here]) are still present within my general browser window.
For one example, I tend to keep a single browser instance at 1024px width and tab the crap out of everything, but I like Google Calendar to be full screen — Mozilla Prism allows me to be neurotic without negatively affecting my work flow (point in case: maximizing and restoring Firefox over and over).
Additionally, when I have a whole browser window dedicated to a locked GMail tab, I don't really need to look at my bookmarks or an address bar. These tend to make me turn my supposedly "dedicated" Firefox window into another general browsing window with a multitude of tabs, at which point I get too disorganized (across multiple general browsing windows) to be optimally productive. Mozilla prism spawns a new single-URI instance on click, which prevents me from digressing too much.
In the end, I guess the minimalism that comes with the separation of concerns just tends to jive well with my routine work flow. Kudos to the project for coming up with and implementing an idea that I never would have — despite its theoretical disadvantages, I've certainly enjoyed it in practice.
I should probably also mention that I'd be very surprised if Mozilla Prism were designed with my needs in mind. I've been assuming that the whole impetus for the project was to give things like Google Docs the look and feel that rivals that of native applications, as opposed to using launchers that affect your web browser.
The difference between URIs and URLs is explained on Wikipedia.