The new 3D styled Dock in Leopard is looking very stylish, but I think the 2D style which is used by the Dock when located on the left or right screen border is more functional. It is also possible to change the Dock on the lower screen Border to the 2D look. To do this you need to open the terminal and enter:

defaults write com.apple.dock no-glass -boolean YES
killall Dock

To switch back to the 3D style, you can use the following commands:

defaults write com.apple.dock no-glass -boolean NO
killall Dock