Tom Forsyth, who is currently at Oculus, was once on the core Larrabee team at Intel. Just prior to Intel's IDF conference in San Francisco, which Ryan is at and covering as I type this, Tom wrote a blog post that outlined the project and its design goals, including why it didn't hit market as a graphics device. He even goes into the details of the graphics architecture, which was almost entirely in software apart from texture units and video out. For instance, Larrabee was running FreeBSD with a program, called DirectXGfx, that gave it the DirectX 11 feature set — and it worked on hundreds of titles, too.
Also, if you found the discussion interesting, then there is plenty of content from back in the day to browse. A good example is an Intel Developer Zone post from Michael Abrash that discussed software rasterization, doing so with several really interesting stories.