The server is called The Gay Motherland, and it's there that we explicitly explore light socialism. There aren't many great pressures because ours is primarily a post-scarcity economy. There are certainly some pressures and rare resources, but not many, and Minecraft itself is not geared towards scarcity in general, though a limiting factor can be computing power.
My particular commune (a loose collection of players working towards some rather nebulous goals) is anti-slavery, anti-homophobic, environmentalist, and conservationist, and most of us like to strike out and explore.
Another long-term project we have is one I'm part of - to go very far out into the world, to build a method of transport back to civilization, and after doing so, to build an epic hollow mountain upon a large sea, containing a magical village at sea level.
In this project, I will write blog posts comparing the way most players and servers play versus how we play, and in general, the surprising (to me) success we've had playing to ethical rules on top of the natural limitations of the game itself.