To be clear, although it seems Asus Transformer-ish, look under the "Laptops & Hybrids" section of HP's website -- not tablets -- (or here) if you want to order the device.
The laptop-tablet hybrid was originally scheduled to be available in August. It's listed with the full name HP SlateBook 10-h010nr x2, and is branded as a "PC," even despite its Android Jelly Bean (4.2) non-Windows 8 roots.
The SlateBook x2 is powered by NVIDIA's latest ARM system-on-a-chip (SOC), the quad-core Tegra 4. It sports a 10.1-inch 1,920 x 1,200-pixel display, 16GB of internal storage, and 2GB of RAM. It ships with a full island-style keyboard. The magnetic docking mechanism, HP boasts, makes it easy to switch to laptop mode.
It also ships with wi-fi and Bluetooth support, front- and rear-facing cameras, and -- yes -- a touchpad as part of the keyboard.
It sells for $479 directly from HP, but it will undoubtedly show up elsewhere, possibly discounted.
HP has been selling a similar Windows 8-based hybrid for some time. The Envy x2 is an 11.6-inch laptop-tablet hybrid that runs Windows 8 using an Intel Atom processor.