It's still working in GM using a Magic Mouse: two fingers double tap on the icon.
I actually meant using the wheel on an old fashioned mouse but no mater....
Just looking at the expose setup in DP 1 again, with that action on the Dock icon for each app and, it is overall much neater than the set up in Older versions of OS X. Barring being attached to the old way of using spaces, it is better in that Expose is exclusive to each app. This means that there is less of a cluttered visual experience where before every window that was open from every app had to be seen. In Lion it is better because you generally know which app the window you are looking for hides in so you can Expose it through the Dock app icon. Another aspect which is better is that the Expose shows all the windows for the app no matter which Space they are in. Another nice touch is for apps like text edit where recent files also appear under the devising line for hidden windows.
Moving on to Mission Control, which I originally hated and if one is not hung up on having 16 spaces (4x4) for their workflow, it is in many ways more intuitive, keeping the more mundane task of moving stuff between space separate from Expose. In Lion you can grab just one window to move or all the windows for an app by dragging its icon. In the Leopards to move all windows you had to press some key or other, proving the point that it was a lot less intuitive because for the life of me i can't remember the operator key, I used it so rarely.
One other tidbit. In Finder when using the new arrangement feature where files are segregated into rows and appear in coverflow form, if you don't have one of the new fangled HIDs and just use an old fashioned mouse, you can scroll forward by clicking at the right hand side of the finder view row or back by doing so on the left. Nice touch.
Lastly, I an noticing as I type this some nice blue hatched underlining on some word as I type. Not red or green, just blue. What does this signify and what outrageous sin am I committing against the English language?