Rated 4 out of 5 stars
I am a big fan of Prism/Refractor add-on, so I am very sad to say that: Prism became an INACTIVE project of Mozilla Labs!
Mozilla Labs has not been working actively on Prism since early 2008. The team responsible for development of Prism, on the past 3 years, set up Salsita Software few months ago to focus on the ongoing development of WebRunner: Prism is now WebRunner! Last February, Prism was renamed back to its first name, according to Salsita.
WebRunner (former Prism) still free, available for downloading (as FF add-on XPI v4.0b12 only), at salsitasoft.com, and open-source available at Trac project.
My last words for Prism: I practically don't use Bookmarks anymore, my often-visited sites are ALL in Prism in my Start menu and Desktop. Prism is a plain, fast 40MB RAM Firefox... a FF with some add-ons can easily reaches to 160MB RAM. Thanks, Mozilla Labs.
For you, Prism addicts, I give you my last advice: the best Prism platform I found is FF3.5* + Prism 1.0b2. I suggest to keep a separated FF3.5 installation (from 3.6 or 4.0) just to create your Prism applications.
Prism 1.0b3 have some problems with window buttons depending on the add-ons installed in FF.
Prism 1.0b2 is not compatible with FF3.6 (there is shortcut for that but) some sites can't even start if application is created into FF3.6 (again) depending on the add-ons installed in FF.
We all know that few features are missing on Prism, but I will give WebRunner a try (I don't like the name, I don't like the logo), if it does not work better than Prism I will keep the platform described above.