10.7: Have a custom Dock per Space
: An awesome new feature in OSX Lion that is easily overlooked is the ability to customize the Dock in each Space.
By right clicking or Ctrl+clicking on a dock icon and then going to ‘Options’ you will notice the ability to assign that icon to ‘All Desktops’, ‘This Desktop’ or ‘None’. None is set by default.
A simple yet useful feature that was requested so many times in Snow Leopard.
[crarko adds: This is legitimately cool if you like to use custom Spaces, and a good follow-up to this hint.]
Source: Mac OS X Hints