On the left is an instant messenger app called Adium (free,
http://www.adiumx.com/ ). Using the Adium Extra
HUD (also free), you can customize your contact list to look just like the one in the picture.
The dock icons used in the picture are here:
http://skm-industries.deviantart.com/art/TABDicons-66004498
You can use CandyBar ($29,
http://www.panic.com/candybar/ ) to customize all of the system icons (as well as the dock icons) quickly and easily.
*Phew* I hope this post helped you out!