Modules that make up the Core:
StateManager? -- Maintains the State of each Node, maintains the graph of Nodes. Is like a database, holds NodeInstances, which contains live data.
Scheduler -- calls back special ops for each Node at the Right Time. Codename: "Time Machine"
Network -- to talk to other Cores, uses XML (maybe) Broadcasts to other Cores it's location and capabilities.
Persistence -- to load/save the Nodes, possibly using ZODB. NodeInstances must be pickleable. If the GUI stores everything in NodeInstances, it won't need to save anything.