PS3 sphere... is that what its called now? and no... it isnt. Natal will be far and away more successful than the wand.
Based on what, MSs legendary history of succesful casual games ?
Sonys waggle has the benefit of being alot like Wiis, people will adopt it much easier then natal. Hell my gf wants it cause its like wii and iam probably gonna get stuck buying that wagglla. But better buying that then a wii.
You probably will see PS3/Wii games form 3rd partys, with PS3 far far superior graphics setting them apart. Less risk making a Wii/PS3 game then making a 360 only casual game.
Some common sense dude Natal has simple logistics going agianst it, has MS tiny 1st party comapred to Sonys huge.