I always saw [serialized variables] as save games: here's something actively doing its thing, and when it gets converted into a serialized variable, that's like the save state file for it. Is that right?

Yeah, it's almost exactly like that. We use serialized variables not just for networking, but because it's serialized... it doesn't necessarily need to be a network. You've got this serialization process that converts from, I suppose, the native format that the program's running with into a normal format, and it could be the network, it could be a save game file, it could be the persistent database. So we use serialized variables for those three things.