Looks like Mozilla is breathing new life into the Webrunner application and renaming it Prism. Perhaps based on the success of Adobe Air? Mozilla describes Prism as:
“Prism is an application that lets users split web applications out of their browser and run them directly on their desktop.
Unlike Adobe AIR and Microsoft Silverlight, we’re not building a proprietary platform to replace the web. We think the web is a powerful and open platform for this sort of innovation, so our goal is to identify and facilitate the development of enhancements that bring the advantages of desktop apps to the web platform.”
You can read more about it on the Mozilla labs site.