No, seriously, it's hardly KSR's most famous novel, but it's highly underrated, so go read it, and then come read this. (All my other thoughts on eps 68-69 are in the thread that Mickjeo started, so go read those instead.)
Ok. Here's the thing. Icehenge seems obviously inspired by Wolfe's Fifth Head of Cerberus. (KSR is, of course, a huge Wolfe fan.) Like 5th Head, it's a novel made up of three novellas, with questions about the historical status of the various texts in it.
But my new thought is that KSR might have independently come to the same interpretation of Fifth Head as Glenn and Brandon did, and written Icehenge in response to that reading. There's some similarities there, although KSR is not as subtle as Wolfe.
Recall the structure of KSR's trilogy: the first is a personal account of a person caught up in a rebellion. The second is the personal account of an archeologist studying that rebellion. The reader starts by feeling smug, thinking we know the truth (because we've read the first text telling us how it all went down)... until, halfway through novella #2, when the archeologist finds the text of novella #1. What was data, which we took straight, now becomes just a piece of evidence in the archeologist's case.... shaking our belief somewhat, but still we believe as the archeologist does.
Until novella #3, when a different researcher proves that the text of novella #1, and the other evidence found in novella #2, is a forgery.
It's the same idea, sorta, as G & B's idea of 5th Head: we start with premises, taking them for granted, only to have the statuses of the texts undermined, and, at last, the entire edifice collapse. Again, KSR does the collapsing (in novella #3) rather explicitly, so it's different from Wolfe, even if he does play some marvelous expectation games with the reader over the course of a first reading.