The article is pretty light on details. What exactly defines this as a single "structure"? How do we determine where one cluster ends and another begins?

When we see things like this it gets the sci-fi nerd going in me and makes me wonder if we could possibly be seeing the formation of a Tipler Cylinder (http://en.wikipedia.org/wiki/Tipler_cylinder) or similar structure. Or if it's a time-bubble so that a civilization can survive to discover other sentient life.

If its so large, why is it a cluster? I didn't know the universe was that large...sounds like these objects are actually scattered fairly thinly.

Also, gotta love astronomers and their affinity to naming things:

"For simplicity we shall also refer to U1.27 as the Huge-LQG and U1.28 as the CCLQG"