A developer friend of mine sent me another few tidbits about Snow Leopard, rumoured for release next week.
The feature mimics the functionality found in the Windows Taskbar, where application windows get minimised into the application icon, as opposed to OS X (Leopard) where minimised windows occupy space on the right hand side of the dock.
Well, in Snow Leopard, there's a new preference in the Dock settings in System Preferences:
When that box is ticked any window you minimise actually disappears behind the application icon, like this:
A couple of other changes in Snow Leopard that he noticed;
Google Maps integration into the date/time control panel:
and a new security preference for a time delay when entering a password after sleep: