Here is the description made by the author himself:
WP CODA is a theme created by modifying several already-existing code snippets and implementing them with my own design. The result is a wordpress theme that mimics the functionality of the very popular Coda website that is the object of so many developers envy. Every aspect of the Coda website was duplicated and this theme works in every major browser.
And as images worth sometimes more than words themselves, I advise you to go have a look!
WordPress Theme: WP Coda