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!