This may be old news for some, but according to a recent arstechnica article, the B2G team is set to give a demo at Mobile World Congress (MWC).
>From the article, a very high level view of B2G is: The B2G platform consists of three main layers. The bottom layer, which is called Gonk, includes the Linux kernel, the hardware abstraction layer, the telephony stack, and other low-level system components. The middle layer is the Gecko rendering engine, which has been improved with new APIs that expose device capabilities. The top layer is Gaia, the B2G user interface, which is built entirely with HTML and JavaScript.

