I have "Spaces" assigned to the "Spotlight" key at the top of the mouse.
It stopped working under Snow Leopard. Assigning a key press to the Spotlight button on the mouse via didn't seem to be an option, because Spaces only lets you assign F-keys to the Spaces function and LCC doesn't seem to provide a way to use F-keys (that I could figure out).
What I did alternatively that works great is, in LCC, I assigned "Advance Click" to the Spotlight button, and selected the click to generate a "mouse button 8" event.
Then in the Spaces preferences assigned Mouse button 8 as the trigger button to activate the Space zoom out function.
And whalla!
It works faster in Snow Leopard than it did in Leopard. Also in Leopard there was a glitch
where sometimes the Spaces would do a slow pan out and back in, which I never wanted.