Everything you wat to know about the ZuneHD is available at the Microsoft store–give or take a few details, oh, like, the Nvidia Tegra chip. The San Francisco Chronicle says this about the Nvidia Tegra:

When Nvidia talks about Tegra APX 2600, they mention it having “eight processors” integrated into a system-on-chip (SoC). These are the HD Video Decoder, HD Video Encoder, 2D Engine, Imaging, GPU (3D graphics), Audio, and two ARM cores. The APX 2600 uses the ARM11 MPCore chip, which can contain anywhere from one to four cores; Nvidia’s configuration is two. These CPU cores are essentially similar to the single ARM11 core in the iPod Touch and first two generations of iPhone, though the iPhone 3GS has a more powerful ARM Cortex A8 core.

How much processing power ZuneHD actually has we still don’t know. But for other items on the specs list, like video support (e.g. H.264 video at 720 x 480 at 30 fps or 720 pixels x 576 at 25 fps) or HDMI output, which requires a dock are all available at the product page.