@Greg:
Again, it makes perfect sense when you think about who's been doing what.
I just never really considered it before.
The way I always figured it was that Cipher Pol along with any number of other organizations was probably under the direction of a Cabinet (or Ministry or whatever) level position and would report directly to the Gorosei. Seeing as how we don't get any new names or organizations, I doubt this is the whole story.
At a guess, the chart in its entirety would look more like this:
….Gorosei
….....|
World Nobles
….....|
….....|______________________________________________
….....|…..............................|…...................................|
….....|…..............….............|…...................................|
…Ministry of Defense…...Intelligence Agencies….....Shichibukai
….....|…..............................|
….....|….........................Cipher Pol
….....|___________________________________________________
….....|….................................|…........................................|
Department of the Navy…..Judical System …....................Penal System
Below the Department of the Navy, you're have Naval Intelligence, Research and Development and so on.
Anyway, Spandine is probably Secretary of Intelligence Operations (or something along those lines) while Sengoku has a civilian boss who coordinates operations with other Directors.
Of course, there are probably things like Department of Public Works (upkeep on facilities alone has to be a major part of the World Government's budget), Department of the Treasury (seeing as how there's an almost universal currency and an exchange rate for at least one of the two other currencies we see), and so, but they're not worth bothering with right now.