The nests looks like an intricately woven tapestry, its subtle browns and gray patterns looking like different geological rock strata. They are in fact, also according to Meyer, wood fibers (you can see leaves sticking out of parts of the nest) mixed with saliva to make the comb. The latter was divided into different levels, all of which had these perfect hexagons. Why in hexagons? Well, Robert Krulwich from RadioLab provides an explanation — it basically comes down to what's most efficient and compact. I recommend you check out the link as it's fascinating that this efficiency theory was made over 2,000 years ago, but proven mathematically only recently. (The link in the RadioLab piece to the article that proves it is broken, so here it is in case you want to follow the math.)
If you look closely at some of the pictures, you can see that some of the hexagon cells were still filled in. Some had larvae that had died in various stages of development, and one had an almost-fully formed specimen. I carefully got it out and indeed, it matches a wasp description. Bees are generally broader and wasps more streamlined and the former are also hairier, which facilitates their pollen-carrying capacity. The little dude I found had very little hair and had a smoother and leaner thorax area. Now, there are some bees that look like wasps, so I hope I identified the little guy right, but from what I can see of it and its nest, it looks wasp-ish. Any entomologists out there, let me know! Finally, if you're interested, the folks at RadioLab once again provide some excellent material -- their "Emergence" podcast examines in part how individual social insects (of which some bees and wasps are) become part of a hierarchical group that functions as a unit to survive. It's fascinating.
Anyway, it was a good Sunday-morning discovery — if only all Sundays started out so well!