The majority of set-top boxes running XBMC are Android-powered devices. However, The Little Black Box is an Linux-powered set-top device that arrives with XBMC pre-installed.
Key specs? The set-top box is loaded with an MLogic AML8726-M3 @ 1 GHz chip paired with 1 GB of RAM.
Additional hardware features include 4GB Flash, HDMI, AV output, HDMI output, Ethernet, WiFi 2x USB host ports, power supply and a dual-sided RF remote with a QWERTY keyboard.
The Little Black Box is slated to ship at the end of May and can be pre-ordered for $99 Euros or $130 here, with free shipping to destinations in the US and Europe.
As the folks at CNX-Software note, while the exact source code used in the device will not be made completely available, there should be a TLBB version (closed source) shipping with the product, as well as a community build which will be fully open source.