It still needs a bit of work, but FF coming out of the gate with video tag support is going to create a huge push for the eventual demise of the .flv format, which should never have been birthed to begin with, and wouldn't have, had 'everyone' started thinking about interoperability from the get go.

FF's continual gobbling up of market share will, hopefully, help further the development of the open video formats like .ogg, so they become truly viable for everyone.