"Zone" implementation ideas??

What does a "zone" mean? Is it just a trigger shape, so that you can tell whether a goal is accomplished? Is it a "walk mesh" that designates where entities can walk? Is it a rule zone where different rules (say, gravity) apply? Something else?

If you have an octree class, you can probably templatize it, so that you can instantiate two of it -- one for rendering, and one for zones. Then put your zones as convex objects into the octree (convex, because it's much faster to test for) -- rectilinear blocks, spheres, possibly prisms created by extruding a polygon in 3D (easy to test for if you only test "center within" not "intersection of volumes").

When I used the term "zone", for this particular project its used for spawn regions. At any given point in a zone the player is given the chance to spawn to another "spawn zone". I guess you're right in the fact that I can use the octree as a structure to implement this. I'm gonna think this through and see what happens. Thank you.

In all games I've looked at, a Zone as you describe it is simply an invisible primitive placed in the map, be it a cube or a sphere or what not. If you've got any type of collision checking (bounding boxes, etc), you've got the code to check if a player is in, entered, exited a zone.