One of the questions I get asked all of the time when I demo something in IE is, "Will this work in Firefox?" It's a really good question especially when using technologies like OWA, web access to admin tools, etc. Recently we shipped a new set of visualization technologies on Silverlight.
Matt Hester recently recorded a screencast on Silverlight and one of the highlighted applications is Tafiti. In his initial recording he spoke about the fact Silverlight will run on other platforms and browsers so I suggested he re-record the screencast and add a demo of Silverlight running inside Firefox. Matt did a great job on that.