The new developer's Snow Leopard build, build 10A394, is interesting in that you don't have to reinstall your entire OS to get it—you can just grab it via Software Update.
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Dock Expose finally shows up as well. The OS is pretty stable for everyday use (minus plugins and some apps that don't quite work), so if you're adventurous and don't mind having incompatibilities for some stuff, you can probably find this online somewhere. [Gear Live]