Looks to me like they are using mac4lin, you can get some info and a link from HERE
You can set up your desktop to look just like a mac OSX system.
I didn't/don't like the plain look of the mac but I do like the menu bar at the bottom, so I set up my system with that. HERE
is a pic of my desktop. I am running Debian stable/lenny with Compiz (needed for the task bar), the task bar is called avant and the program to configure it is called AWN. The task bar acts just like a mac one, when the courser is hovered over one of the icons they spin in 3D. If you look around some on the first link you will find all the info you need. If you have problems I can find some links I went to to set my system up. The clock and calendar are a program called gDesklets
all but the Eterm terminal windows start as soon as I log into the desktop.
EDIT:Sorry about the quality of the desktop pic, I had to shrink it to 100kb, but you get an idea still the same. Oh and you can change how the task bar icons act, there are about 10 or so different setting for them from bounce to 3D spin with a spotlight on them.