Agreed. Save all those folks for some big "inspired-by" dungeon or something. Something Jayquaysed to heck, and packaged in an awesome box set with tons of poster maps. Probably with a Beadle & Grimm special edition or something ;-)Honestly, I'd rather all those people did their own takes on a Castle Greyhawk-style complex. I think we'd lose a lot of what makes those folks' special if they were forced to sing cover songs.
For the Castle Greyhawk/Zagyg fans, what many really want is probably the same thing Rob Kuntz did with El Raja Key: just a massive dump of the home notes, history, and commentary. These were living campaigns over a very long period of time; many want to see that as it was actually used/played. Commentary from the designer might be tough, but interviews with the players would certainly provide some wonderful stuff.
IMHO, any other version is just that: yet another version of Not-Gary's-Castle-Greyhawk. Those things are cool and all, but as I'm finding out more and more, they are simply somebody else's fun-house dungeon with all sorts of randomness and little cohesion to it. The tools to build that already exist and are just fine: the 0E and 1E encounter tables, the AD&D DMG random dungeon generator, and the old geomorphs. I don't particularly find Castle of the Mad Archmage, Greyhawk Ruins, or anything of that ilk to be compellingly better. Their main benefit is that they are simply done (published, complete, already packaged). But they aren't Gary's dungeon.