What is non-buddhism? I've been off and on following the writings Glenn Wallis, et al. 

I am honestly bemused at what they are driving at. I don't mind that there are critical of something about various parts of modern Buddhism-- it's good to read criticism and write apologia, but much of it is couched in a certain, I don't know, "grad school" style.

What is non-buddhism? Is it some sort of pro-Buddhist Buddhist reform movement, or more as atheism is to Christianity?
OK, I'll have a go, based on my (re-)reading of Wallis himself at his "What Is Non-Buddhism?" page. First, I have to say that one possibility is, it's an elaborate joke or hoax. The page says almost nothing substantial, except to offer analogies with non-Euclidean geometry or Laruelle. He says mostly what non-Buddhism is like and what it is not, but very little about what it actually is. But giving the benefit of the doubt:

His point seems to be that the label "Buddhism" may be attacheable to something valuable but that "x-Buddhism" -- i.e. all the "regular" forms of Buddhism, its types and sects and lineages, and their thought, practice, culture, and so on -- sit within a framework that pretty much makes it impossible to get to that something valuable. Therefore, in order to investigate the heart of the matter, you have to stand outside the x- stuff, and take a view from there. It's an attempt to apply Laruelle's "non-philosophy" specifically to Buddhism.

On the one hand it could be much ado about nothing. It's not completely false, but to the extent that it's true it seems kinda obvious. On the other hand, it certainly is possible for there to be deep, undetected aspects of human discourse and culture that, despite being undetected, have significant impacts on our way of life, and sometimes those impacts can be limiting and negative. So it may not be as obvious as I think.

Here's an analogy. Once upon a time, Aristotle codified logic. It was cool, and helped us figure out if arguments were valid. But it wasn't powerful enough to handle certain kinds of argument. Fast forward 2000 years, and in comes Frege. He produces a much more powerful form of logic, and also helps us understand what math is. But he makes a crucial mistake. So in comes Russel, and he fixes Frege's mistake. Or, at least he thinks he does. Then in comes Wittgenstein to show not only that Russel's fix wasn't complete, but that the whole thing just wasn't fixable at all. A few years later, Goedel belts the final nail in the coffin of a specific portion of the problem, but in such spectacular fashion that everyone sits up and says "WTF!?"

The point is, Wittgenstein and Goedel spotted that not only were prior systems broken, but that they were so fundamentally broken they were simply not fixable from inside those systems. To give Wallis etc the benefit of the doubt, I think they're arguing something similar (I'm stretching my analogy very thin now) about Buddhism. It's so busted that to fix it they have to step outside it.