> I've always wondered why smaller MMORPGs use multiple servers. I've never seen any upside to it. More hardware maintenance, a fractured player base, and server merges if populations dwindle on certain servers.

I'm not sure you can easily get that many people into a single server. EVE does it by partitioning known space into very small isolated "systems" with defined transit points between, and even then they've done some fairly impressive stuff to get that many uses into a shared system...

For a nice comparison, see Second Life, where the grid spends most weekends screaming under the load...