In an interview with Famitsu, the development team behind the Nintendo 3DS gives some info on how the development process to the 3DS occurred over time.
The original plan was for the DS successor to have 2 screens since backwards compatibility was their main goal and then start to add new features.
Around 2008, the team decided to test out 3D to see how it would look on a screen with the goal being glasses-less 3D. They did this by hooking a 3D tv to a Wii and used Mario Kart Wii. Everyone liked it soo much that it was implemented in the 3DS.
Late into the planning and development, Miyamoto requested gyrosensors as a way to add a new type of gameplay for games not 3D-dependent. He wanted some form of motion controls on a handheld ever since the Wii was released and as another new type of gameplay.
The gyrosensor ended up becoming a backup plan for games not 3D-dependent but wanted to stand out in the 3DS library.
http://kotaku.com/#!5768054/3d-wasnt...ed-for-the-3ds
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Microsoft announces Gears of War 3 release date pushed back from a March/April 2011 date to now September 20 and as a global release.
The delay was not due to development problems but a marketing decision by Microsoft and also gives Epic Games more time to have the beta trial for the game.