I don't have my Pi yet and I am not going to muck about with Virtual Machines but I have been wondering about instruction set for the Broadcom chip. From what JamesH says in his post he infers that this is not available. Is it worth exploring the Broadcom web site? I thought it may be a cut down from the i386. Does the Pi in any of its software forms run the Bless Hex editor?
The Pi's Broadcom chip is basically a GPU with an attached ARM core. ARM, not x86. You'll find plenty of information about the ARM assembler language in the ARM architecture reference manual (ARM ARM), in books, online, etc.
However, you will not find public information about the GPU, a Broadcom Videocore IV, partly designed by Eben himself. To access that kind of information you'd have to have deep pockets and be willing to sign an NDA.
Reverse engineering may be possible, but you'd rather be really experienced in that kind of stuff and in GPU coding in general to do so.
What Broadcom does is make the binary blob available. It's a compiled piece of software that serves as an interface between the GPU and the system. The blob does the all the magic stuff to make sure some high level graphics stuff is actually offloaded to the powerful GPU. Stuff like 3D graphics using OpenGL ES 2.0, stuff like 2D graphics using OpenVG 1.1.
Those are open standards that are widely used by virtually everyone – because nobody wants to reinvent the wheel every time he writes a 3D or 2D application. You'll find tons of books on OpenGL and even OpenGL ES, the latter getting popular because it's the version that runs all that cool 3D stuff on your Android or Apple smartphone or tablet.
Those are industry standards and I just read today that Eben is chair of the Khronos OpenVG group. Khronos is the consortium where the vendors meet and agree upon common graphics / GPGPU standards (OpenGL, OpenGL ES, OpenVG, OpenCL, …).
So, though I would have liked to get into low level GPU stuff on the Pi myself, it won't be, because BCM has a vital interest to not make all their implementation details on the GPU available to everyone for free.
But we have the standards we can use and that are accelerated and we have the ARM CPU core.
I'm probably going to buy me a PC to play around with OpenCL instead and keep the Pis for other stuff