Someone mentioned that while the idea of concurrence (see earlier post) was neat, they weren't sure how it applied to the game universe in general.

It doesn't apply to the game universe in any given way, as of yet, it's simply a concept. Objects sharing the same space in different universes allow or make much easier travel between universes.

Application would depend on how I handle universes. If I go with a universe is a server then one application would be to allow cross-server communications (between players) near concurrences (near being a relative term, probably in light years).

Perhaps on a newly explored planet that happens to be concurrent, events from the concurrent world show up. While setting up shop players hear voices (chat from the other server on that planet), which would be a way to identify that you found a concurrence.

Alternatively, universes may just be layers on a given server. You have layer Prime, which is our universe, and subsequent universes are rated P+/-x. P+3 would be three universes away. As you get further out, things start becoming radically different. In this model, the game starts with 3 universes, P-1, P0, and P+1. Where there is concurrence the concurrent object in P+1 or P-1 will be an almost exact copy of the object in P0. From there travel to P+/-2 may be possible (a new universe is generated in a given P direction whenever a layer is "discovered" (i.e. moved into).

I'll probably go with the latter (Prime) model but I'm not ruling out turning universes into servers.