For a long time various people have been telling me there's not much information on the low-level / plumbing details of the virt stack on Linux. Especially information related to qemu and its various settings, devices, and so on.
Documentation surely is difficult to come by, but a quick and straightforward solution is to syndicate all of the blog posts that people doing virt development write into a common stream: a planet virt. I started hosting and testing such an instance on openshift, but was quickly pointed to the existing Virt Tools Planet by Rich Jones and Dan Berrange. Dan added the list of people whose blogs I followed for virt development to that instance.