In Mozilla's words, "Prism is an application that lets users split Web applications out of their browser and run them directly on their desktop." In practical terms, that means you can have individual browser windows dedicated to specific Web applications--like Gmail, Facebook or Twitter--without having to worry about them becoming mixed up with your other Firefox tabs or needing to be restarted if you restart your browser.
Pretty much any website can be set up to run in Prism, but since Ubuntu 8.04, the Ubuntu repositories have offered a number of preconfigured Prism packages for popular Web applications. In Ubuntu 9.10, these include Facebook, Twitter and Google Mail, Analytics, Calendar, Docs, Reader, Groups and Talk.
That means installing Gmail via Prism in Ubuntu is as easy as clicking the prism-google-mail package in the Software Center, or typing "apt-get install prism-google-mail." After that, accessing Gmail is as simple as navigating to Applications>Internet>Google Mail, like so:
Why it mattersPrism is not very new, nor is it a revolutionary concept. And it doesn't provide any functionality that's not already available from Ubuntu by default; it just makes things a little more convenient.
Nonetheless, it's stuff like this that Canonical should be pushing as Web applications and other aspects of "the cloud" move to the forefront of desktop computing.
If Ubuntu wants to prove that it's easier and more convenient than Windows, and if Canonical hopes to compete with emerging Web-oriented operating systems like Google's Chrome, Ubuntu developers should focus on demonstrating how quickly and simply Web applications can be installed as if they were standalone desktop programs.
One of the things I don't like about Chrome is that it wants to force everything into the browser. Sometimes I still want the flexibility and discreetness of standalone applications. Prism is a good compromise between the two extremes.
The fusion of the traditional desktop with services hosted remotely is the future, and Ubuntu's packages for Prism are a great example of how convenient that development can be for users. But the users need to know about it first.