Dave Arneson's birthday. The co-creator of D&D is of course famous for Blackmoor, which is a setting in its own right yet inexplicably part of the World of Greyhawk as well. That got me rethinking how Greyhawk, the setting many of us love is really an ugly patchwork of disparate settings, genres and authorial voices. Contrast that with rival Forgotten Realms, and you'll see why Greyhawk isn't a very marketable setting as a whole.
I'm not a Gygax historian by any means so my facts and chronology might be skewed, but I do know enough about the setting that I can look at the parts that make up the whole and see how hard it would be to defend the setting to a newcomer. The basis for the World of Greyhawk is naturally, an adaptation of Gary's home game and if I'm right Robert Kuntz's Maure Castle game as well. It's not uncommon for writers to collaborate on fantasy settings; Dragonlance is a successful example. A couple DMs building a homebrew world is ideal in fact, though Gygax does get a lion's share of the credit. Ed Greenwood by comparison is also considered the singular voice behind the Forgotten Realms but it's early development wasn't burdened by additional or outside the home setting material (cultural analogs Kara-Tur and Al-Qadim notwithstanding). Greyhawk however, during the infancy of D&D was intentionally designed to be a kitchen sink setting that liberally borrowed from many of TSR's brightest authors.
Lenard Lakofka's Lendore Isles campaign nestled comfortably on the edge of the map. Jim Ward's classic sci-fi game Metamorphosis Alpha was given a nod in the World of Greyhawk via the adventure Expedition to the Barrier Peaks. Genre bending hero Murlynd features heavily in early Greyhawk canon and I suspect he may have once been intended as a link to TSR's western-themed RPG, Boot Hill. Stranger yet is author Andre Norton's involvement in writing the novel Quag Keep. It's name is also thrown in the game setting despite there being no further similarity.
The patchwork nature of the setting goes "beyond the Flanaess" too, the setting nearly saw the inclusion of Frank Mentzer's Aquaria setting and it's now fairly well known from the Dragon Annual #1 map of Oerth that much of what was planned to be in the western half of the world was somehow based on the French graphic novel Black Moon Chronicles. By the time all these things are in place, the incorporation of Moldvay and Cook's classic The Isle of Dread into Oerth for Paizo's Savage Tide AP seems even less surprising.
So what is a fan of Greyhawk to think? Luckily the setting has been around long enough that later writers and fans have done all the heavy work justifying how these parts work (or don't work) together. Or you can ignore ramblings like mine and enjoy the diversity. Yet for published Greyhawk to continue one day or even reboot as the case may be, I'm afraid it may be necessary to tear up this quilt and focus just on the cohesive or "iconic" parts of the setting.