Today a new build of Snow came via the software updater. The new update includes Dock Exposé. To activate Dock Exposé click and hold on a running application's Dock icon and then clicking any other running application to switch to that application's Exposé. The new Dock Exposé also shows any applications minimized to it's Dock icon in a lower panel.
Spoiler for Screenshot:
It would be best to view the video in HQ and full screen.