I thought I'd do a post on the relationship between my upcoming co-DMed Greyhawk Campaign and the Folio Project. The short answer is that the campaign will take place in a Greyhawk that is more familiar to my co-DM. There will be some changes to the standard canon (notably in the deities and at least one of the cultures) but for the most part it's the Greyhawk one imagines when one hears the word Greyhawk.
I should note that I don't know how true that last statement is. As I mentioned when I first started that project, prior to purchasing the original Folio I had no experience with Greyhawk. I've come to enjoy the setting and to view it as a land of "shining kingdoms."
My version of Castle Greyhawk is definitely going to be my version of Castle Greyhawk. Notably, I'm changing the creator of the dungeon from Zagig to Vennax Nalk's Kin (or Vennax the Mad). I had originally developed this toad god worshipping madman for my entry on the Great Kingdom. He'll obviously be changed quite a bit.
I'm not sure whether or not I'll continue the Folio project. I'll obviously be more immersed in Greyhawk in the coming months, but it is definitely not the Greyhawk I envisioned when I started the feature. Only time will tell.