From what I understand, the Wii will allow you access to the raw data (orientation of gravity, gyros, IR and buttons), just like the PS3 wand does, but there is 1st and 3rd party software available to generate "gesture" data so you don't have to figure out all that stuff yourself. Raw position data is much harder to work with, which is why 3rd parties created libraries to handle that in the first place. There have even been demo videos released to the public about these libraries. Ultimately they will have to create similar libraries for the PS3 as "gestures" are incredibly important. You don't want people to have to follow a precise path relative to the screen, you want them to execute a "gesture" as not everything can be 1:1.
However, according to this, the PS3 will report relative position to the screen directly, which the Wii does not have that capability unless the software developer programs it in themselves which is harder to achieve. This gives programming for the PS3 the edge, as even Nintendo had a hard time getting 1:1 working due to resynch issues.








