Let's get started shall we?

System Specs:

Launches: 2012

Size: Approximately 1.8 inches tall, 6.8 inches wide and 10.5 inches long.

New Controller: The new controller incorporates a 6.2-inch, 16:9 touch screen and traditional button
controls, including two analog Circle Pads. This combination removes the traditional
barriers between games, players and the TV by creating a second window into the
video game world. The rechargeable controller includes a Power button, Home
button, +Control Pad, A/B/X/Y buttons, L/R buttons and ZL/ZR buttons. It includes a
built-in accelerometer and gyroscope, rumble feature, camera, a microphone, stereo
speakers, a sensor strip and a stylus.

Other Controls: Up to four Wii Remote™ (or Wii Remote Plus) controllers can be connected at once.
The new console supports all Wii™ controllers and input devices, including the
Nunchuk™ controller, Classic Controller™, Classic Controller Pro™ and Wii Balance
Board™.

Media: A single self-loading media bay will play 12-centimeter proprietary high-density (25 GB)
optical discs for the new console, as well as 12-centimeter Wii optical discs.

Video Output: Supports 1080p, 1080i, 720p, 480p and 480i. Compatible cables include HDMI,
component, S-video and composite.

Audio Output: Uses AV Multi Out connector. Six-channel PCM linear output through HDMI.

Storage: The console will have internal flash memory, as well as the option to expand its
memory using either an SD memory card or an external USB hard disk drive. 8GB internal flash memory

CPU: IBM Power®-based multi-core microprocessor.

GPU: AMD Radeon™-based High Definition GPU. (most likely a Radeon HD 4850 based card)

Other: Four USB 2.0 connector slots are included. The new console is backward compatible
with Wii games and Wii accessories.

Note: Details are subject to change.

Tech demos:

Zelda WiiU "HD Experience" - http://www.youtube.com/watch?v=arHNcSMXaBk Alternatively: http://www.youtube.com/watch?v=Sdn2YOKP9RU

WiiU Nature Graphics Demo - http://www.gametrailers.com/video/e3-2011-wii-u/715112?type=flv

WiiU "New Controller" Demo - http://www.gametrailers.com/video/e3-2011-wii-u/715305 (this reminds me of Game Boy Advance connectivity, so much)

More WiiU interviews can be found here, in glorious HD: http://www.gametrailers.com/game/wii-u/14932

WiiU tablet resolution: http://golgotron.com/2011/06/nintendo-wii-u-tablet-screen-resolution-revealed/

WiiU comparison to Xbox 360 and PlayStation 3: http://www.randomprodinc.com/wii-u-specs-comparison/ (is this even fair to the HD twins?)

WiiU underwhelms investors: http://www.reuters.com/article/2011/06/08/us-videogames-nintendo-idUSTRE7564TY20110608

Assets available to download: http://www.mediafire.com/wiiuassets

so its a lot like PS3 / Xbox 360 , not more powerful like the rumors have said.

but AMD >>>> nVidia any day

Ehhh...maybe. I know that the 360 GPU is equivalent to an ATI Radeon X1950 card.

From what I've been reading, since it will be using a custom cpu based on a Power 7 architecture (which apparently is the most powerful architecture of IBM CPUs and are more powerful than comparable Intel i7s), depending on how many cores were cut off  and how low the clock speed is decreased to fit energy and temperature requirements iit should be anywhere from a few to many times(I'm not sure how accurate that is) more powerful than the 360s Xenon. Since we should expect a comparable GPU that won't bottleneck the CPU, that also should be a significant upgrade. Will it be an upgrade similar to that of last generation to this generation? More than likely not, but neither should we expect the other next generation consoles to be, especially if they don't want to make similar losses at the start of the generation. So I think it will be safe to say that PS720 will be in the same range as Wii U, and while all of them will be significantly more powerful than what we see now with the HD Twins, the difference won't be as large as that from PS2, Gamecube, Xbox -> PS360.

Here's the thread on Neogaf I was reading about the Wii U's  cpu.

http://www.neogaf.com/forum/showthread.php?t=432965

edit: One more thing, most of the footage used in the montage trailer of WII U games is actually footage of the PS360 versions. Just wanted to make that clear to those who are looking at that for a reference. 

We know that PS3 and XBox 360 are *maxing out at 720P/30fps.

Reggie repeated a few times that WiiU will be 1080P. And going by Nintendo's standard, we'll be getting 60fps.

http://en.wikipedia.org/wiki/PowerPC_A2

The PowerPC A2 is a massively multicore capable and multithreaded 64-bit Power Architecture processor core designed by IBM using the Power ISA v.2.06 specification. Versions of processors based on the A2 core range from a 2.3 GHz version with 16 cores consuming 65 W to a less powerful, four core version, consuming 20 W at 1.4 GHz. Each A2 core is capable of four-way multithreading.

Is another good possibility.

Let's just hope it has enough RAM, although I must say that I doubt it.

If it's anything like the HD 4850, it'll be much more powerful than the GPU of 360 or PS3. 360 has the equivalent of X1900 or X1950 (not sure) while PS3 has the equivalent of GF 7800.

A HD 4850 in it's base configuration is approximately three times more powerful than a 7800GT, and RSX has only 128 bits of memory bus, so it's probable that the gpu in WiiU is at least two and a half times, probably three to four times, more powerful than RSX.

I've been hearing that the nature and zelda tech demos were running in real time but I am a little bit skeptical.

You can control the camera and change the lighting, but nothing else. Zelda tech demos always look worse than the final product though.