Whenever I hear people say "Linux is just about ready", I twinge a bit. There is certainly truth to its increased adoption and suitability for the enterprise, but for the creative professionals that Adobe/Macromedia/etc. market to, how is Linux ready for them?
Linux still is not really for this market at all. For those who aren't hobbyists, or working within an enterprise enviroment (with a dedicated IT team), Linux will probably be overwhelming and cause them to run back to Windows.
What the "Linux desktop system" lacks is a coherent battle plan to target this market. There are some strides being taken here, but IMHO they are still in their infancy and things will change dramatically for Linux in the next two years. Commercial companies who made a significant investment could find themselves forced to adopt new tools and distros due to a changing market, just around the time they're finishing version 1.0 of their Linux port. When the desktop system emerges, I think the Adobes and Macromedias of the world will jump on it. Maybe someone will beat them to it... But having a great app on a desktop that most creative professionals aren't using (and won't knowably use in the near future) just seems like a potentially big failure, ala the Java office suite.