“Prism isn’t a new platform, it’s simply the web platform integrated into the desktop experience,” said the company in the Mozilla Labs blog post. “Web developers don’t have to target it separately, because any application that can run in a modern standards-compliant web browser can run in Prism.”

We gave it a try, installing and launching it without difficulty. A dialog box asks for a web application’s URL, and a name you want to assign to it.

We threw Prism a curveball by adding Yahoo Mail, which promptly complained that it didn’t support the browser we were trying to use. Google Reader worked perfectly, just as it does in Firefox.

Which it should, since Prism creates a dedicated browser window for that application. As one commenter noted on the blog, it’s a Chrome-less popup window.

Since Prism is an early stage product, and unlike the full Firefox browser doesn’t support a web application like Yahoo Mail, Prism isn’t better than a bookmark on Firefox today. How Mozilla chooses to develop Prism will determine its usefulness over later versions.