interesting piece about why id should open-source Doom 3 - to promote innovation from smaller players with fewer resources, to expand the 3d engine market horizontally, to shift innovation pressure to different areas of game design, and, most interestingly, to hypercommoditize it and establish a Doom 3 component of the larger CE electronics platform we all know and love.
Naive strategy tells you open-sourcing would be an idiotic move for id, until after their temporary monopoly's dissipated (which is what they usually do - release their source a few years after their game's been released).
But this piece raises some very nice arguments for a strategic use of open-source, which we will see more and more firms playing with, to shift the competitive dynamics of their markets radically. Put this way, you can see why open-source is so powerful. Highly recommended.