On the official first day of the Electronic Entertainment Expo (E3), the number on everyone’s lips was three—as in 3D.

Both Nintendo and Sony Computer Entertainment unveiled 3D gaming initiatives that raised the eyebrows and pulses of attendees, showing that this current generation of game consoles still has plenty of life left in them for innovation and excitement.

Nintendo struck first this morning with the introduction of the much-rumored 3DS portable gaming device. Like the existing Nintendo DS, the 3DS is a dual-screen, flip-up device with touchscreen trackpad. The difference is that the top screen now displays in 3D, and it has massively increased processing power to handle the additional graphical load.

Unlike most 3D experiences, though, the Nintendo 3DS requires no special glasses. Instead, it appears the device lays an additional screen over the display screen that acts as the 3D glasses for the user, which it can get away with as it’s a smaller and portable device. At times the picture can be blurry, but it features a slider that lets users adjust how extreme a 3D experience they want, and blurry images can easily be sharpened by lowering the meter.

Among the many games announced for the Nintendo 3DS is version of "DJ Hero 2." No demo was shown for how that game would be represented in the new 3D display. Other interesting features of the 3DS include a gyroscope, the ability to take and display photos through an built-in camera also in 3D, and support for as-yet unannounced 3D Hollywood movies. No price or launch date was revealed for the device.

Given the positive reception the Nintendo device received by the otherwise jaded press corps, Sony had its work cut out of it, and largely succeeded. The company told attendees that it would add support for 3D gaming on the PlayStation3 console through a software update, to support a number of game titles being developed for 3D gaming this fall. None of the games are music-related, but the demos provided in the first-person-shooter, sports and racing genres were incredible, and point to an exciting new direction for future music-based games should developers choose to embrace the technology (think a first-person guitar-playing simulation game where the crowd and pyrotechnics are in 3D—replicating the on-stage experience).

Of course Sony’s 3D gaming strategy requires not only 3D glasses, but 3D TVs as well. Good thing Sony has that covered. The electronics giant will bundle three free 3D-capable games with sales of new Bravia 3D TVs once the games become available.

In other Sony news, the company unveiled it’s own motion-capture gaming strategy in response to Microsoft’s Kinetic launch earlier in the week. The PlayStation Move controller (which combines hand-held, Wii-like controllers with a camera/receiver to track movement) will hit the market in the U.S. on Sept. 19. The standalone motion controller will retail for $50, with an additional $30 for the navigation controller. The Eye Camera is sold separately.

Again, not a whole lot of music-games announced for the Move system, except for a new version of Sony’s SingStar title called “SingStar Dance,” as well as yesterday’s unveiling of the as-yet titled Michael Jackson-based dance and singing game.