I’m sure I ran a story similar to this a while back, but I’m damned if I can find it in the Futurismic archives, so I’m gonna mention it anyway: it’s the one about the folk building logic-based processors within the virtual spaces of computer games, the latest example being the insanely popular (and rather lucrative) Minecraft. Find blocks of material with the right in-game properties, chain ’em together, and hey presto, you’ve got a simulated arithmetic processor made of non-existent lumps of an entirely fictional substance. Whole lotta meta, right there.
I think the reason I love these stories is because of the extrapolatory end-point: the implication is that given simulated spaces of sufficient size and complexity (and sufficient player-hours, or clever macros to obviate the need for such), one could build a computing device within that simulation which was itself capable of running a simulation within which another computing device could be simulated. Sort of like Nick Bostrom rewriting Lavie Tidhar’s “In Pacmandu”… it’s simulated turtles all the way down! Now, where’s the door back to my origin reality, please?