Mission Control; how do I correct the order of Desktops? I have 1, 2, 4, 5, 3, 6, 7?

Solution 1:

What you can do is this:

Delete the desktops and then recreate the by hovering over them and pressing the red thing in the corner, then looking at the right to make a new desktop.

This is no longer necessary as of Mac OS Lion 10.7.2, see this answer for an easier solution.

Solution 2:

By default, Spaces are reorganized by last used. You can change this in System Preferences -> Mission Control.

Solution 3:

Starting with Mac OS Lion 10.7.2, you can drag to re-order your desktops, even the ones that are in full-screen mode.

Solution 4:

You can't drag or relocate them even after you disable automatic ortanization in System Preferences -> Mission Control.

They seem to be fixed, which is weird. Let's hope that in a future update, Apple fixes this issue.