Procrastinato on 10 February 2009
The big three have some rules on porting software to their platform -- for example, if you port an old PS2 game to the PSP, you are required to produce a bit more content for it.
Nintendo may very well have prereqs for using the Wiimote in some spiffy manner, before they will allow a 3rd party to make a port to the Wii. They want you to be able to drink a beer and play at the same time.
