IBM leaked a little more its a custom chip based on a mix of power5 and power7 no core count yet though so we can't be sure but it looks like an evolution rather than revolution. Rumor (and die shots) places it at 4 cores and yes speed is an unknown but p7's don't run that much faster than p5's with any great heat efficiency.
The GPU is a long term known it's a modified 48xx generation chip that was dug up in last years financial analysis for AMD
oh and it even features an eDRAM cache...
I read this specs that some people at NeoGAF confirmed as being consistent with the old SDK devs were using: http://www.vgleaks.com/world-premiere-wii-u-specs
This is what it said of the GPU:
- Unified shader architecture executes vertex, geometry, and pixel shaders
- Multi-sample anti-aliasing (2, 4, or 8 samples per pixel)
- Read from multi-sample surfaces in the shader
- 128-bit floating point HDR texture filtering
- High resolution texture support (up to 8192 x 8192)
- Indexed cube map arrays
- 8 render targets
- Independent blend modes per render target
- Pixel coverage sample masking
- Hierarchical Z/stencil buffer
- Early Z test and Fast Z Clear
- Lossless Z & stencil compression
- 2x/4x/8x/16x high quality adaptive anisotropic filtering modes
- sRGB filtering (gamma/degamma) - Tessellation unit
- Stream out support - Compute shader support
I don't think the HD 4xxx supported those characteristics so it may be a highly customized model.