Last week, Gamasutra has published an article about Spore and how it connects to EA/Maxis servers to populate content in the game.  Part 2 has just been added:

Simulated worlds could also become more complex if additional processing power were available to handle the additional workload.  It could be used to simulate activity by far-off empires or other unseen entities, allowing for intelligent and intricate development where developers normally cheat by simplifying the simulation algorithms.  In situations where insufficient resources were available, the game could revert to simple algorithms.

Distributed computing could also be harnessed to make possible new game mechanics that would otherwise overwhelm a single machine.

For example, a time-travel mechanic could allow players to change the course of history and jump between various alternate pasts and futures to see the effects of their actions as determined by the game’s simulation.  Decision points could be set up in advance of the actual jumps, giving the computing network the necessary time to run the needed simulations.   Gameplay mechanics could even shorten or lengthen the gaps between decisions and jumps as necessary, translating fluctuations in available computing power into fluctuations in the game resource needed to travel in time.

article here