"He who pays the piper calls the tune."
"He who creates the pipe controls the tune."
Also true. And infinitely more important.
Consider the recent spat between Apple and Adobe over the alleged unsuitability of Adobe's Flash technology for the iPhone. This is really a battle over what will become the dominant standard (or the "pipe") for video and animations for small screens (smartphones, PDAs, tablet PCs, and so forth). And who gets to create and control that "pipe".