To elaborate, I think Factor 5 made the MusyX sound tools for the N64, then they helped design the GameCube's sound chip, and made the MusyX sound tools for the Cube.
Then they made Dolby Pro-Logic 2 work with videogames, to compensate for the GameCube's lack of Dolby Digital support, and then gave their work back to Dolby, who obviously offered it to any and all interested parties. IIRC, despite all the mocking the Cube got for it, there are more PS2 and Xbox games using DPL2 than there are using Dolby Digital, because DPL2 really is more suitable for interactive videogames than DD is, just like Nintendo/Factor 5 kept saying.
Then they made a DivX tool set so developers complaining about the GameCube's disc size could fit more FMV into their games.
Then they ported their MusyX and DivX tools to the PS2/Xbox, where they were unneeded and largely ignored.
Now it seems that Factor 5 is probably going to be making tools for the PS3. Given Cell's supposed complexity and new ways of doing things, it's probably where they're needed the most.
With the Revolution using the same API as the GameCube, people are probably just going to use the GameCube's MusyX tools as their Revolution audio tools. I mean, does anyone know if they were ever supposed to be "lacking" or anything?