I want to announce that a slide show plus audio of me talking about our Volk library has been published by the IEEE Signal Processing Society here:
http://www.brainshark.com/SPS/vu?pi=zH8zQcV8dzAXPbz0
This is based on a paper and presentation to the Wireless Innovation Forum's annual Software Radio Conference. It goes over the motivation and background of Volk and into how to use it in your own projects. This should extend easily into using it with GNU Radio blocks (and there are plenty of examples of GNU Radio blocks using Volk, as well). It does not explain how to build new kernels in Volk, however. But at 50 minutes, it seemed like it was already going too long.