Spaces in 10.5 worked like this:
Press one key or mouse button to trigger spaces to come up, see multiple screen view.
Move mouse to space you want selected.
Press the *same* trigger key/button, *or* press the left mouse button. Selected Space becomes the active one, zooms in to regular view.

Spaces in 10.6 works the same, except pressing the trigger button no longer works as a selection method – instead, it acts like a cancel and you go back to the space you were in before.The only way to move into the space your mouse is over is to press the select button (left mouse button). This means a button press is added to the process, and in addition, it is different than Expose (where “trigger-move-trigger again” still works).