Both papers were definitely good reads, and of course I too found the blockquote interesting. The second article lays out in a concrete way what I was trying to express with my intuition about "slow, grazing collisions" (as you know, thanks). The Kuiper Belt isn't the inner solar system, and we need to check our assumptions at Neptune.

The first article was interesting for touching on that "cryogenic realm", and it linked to another mind-blowing article: Could a Massive Collision Produce a Subsurface Ocean on Pluto? (io9's a consistently good read, isn't it?). Mlinar's theories seem plausible to this layman, and although they're still looking for the linear surface features that on Europa are believed to be a sign of a subsurface ocean, I have to think those polygonal markings in the smooth surfaces must be a sign of some fluidity underneath. Doesn't have to much, not an actual ocean sloshing around, but even convection is very interesting.

Thanks for the links, podrock.