Yes, I've run several FR campaigns, two Spelljammer campaigns, two Planescape campaigns, two Freeport campaigns etc etc. If I like a setting, I'll try and use it more than once. The Forgotten Realms is huge enough to host dozens of different campaigns.
I run all my campaigns in the same world. Even Rokugan (it's a different continent).
Right now I'm doing one in the Valley of Obelisks and one in Elsir Vale.
Our group shares a home brew setting. Each Dm adds to the world in their own way and sometimes plays off what another has done. Sometimes the campaigns run different time lines, sometimes they're coexisting. It all helps build the world, and its something the players can remember easier since they participated in it.
For D&D3 it's been Forgotten Realms and Homebrew so far (Praemal/Ptolus will surely join the lot, and probably Pathfinder and/or Eberron much later... I am really not ready to stop playing 3E as you can see).
Simple question, do you run multiple campaigns in the same setting? The poll allows for multiple answers, so that you can select for 1e, 2e, 3e, and OD&D.
I not only have for 1E & 3E, I have also used the same campaign world for D&D 3E and other game systems as well (Fantasy Hero, Heroquest, Melanda Land of Mystery).