This is just a recolor for Obsidian based on Ethan Schoonover's Solarized color scheme. Works as of Obsidian 0.6.4.
Find this theme in the Obsidian's community themes browser under Settings > Appearance > Themes.
Alternatively, download Solarized.css to .obsidian/themes in your Vault folder and activate it under Settings > Appearance. (For older versions of Obsidian that do not support themes yet, rename Solarized.css to obsidian.css and place it in the root of your Vault.)