The following details come from the GT.TV interview with Shigeru Miyamoto...
- Miyamoto says Luigi has always had a special place in his heart, but hasn't always had a chance to stand out.
- Miyamoto says that perhaps some day there will come a time where Mario and Luigi need another brother.
- Luigi's Mansion: Dark Moon was created for the 3DS because Nintendo experimented with a 3D screen during development of the original Luigi's Mansion.
- Miyamoto has been working on Luigi's Mansion: Dark Moon for quite some time.
- The Pikmin 3 team is close to Miyamoto's desk, so he's able to work closely with them on a daily basis.
- Miyamoto says Nintendo is working very hard on things for E3. We might get to see things that haven't been mentioned yet, but we'll definitely get to see things that Iwata has shown during Nintendo Direct events.