This is a blue theme based on the Tango color scheme from FreeDesktop.org. The theme is released under the BSD license. There are two Tango Blue themes:
TangoBlue which uses black fonts
TangoBlueLight which uses light blue fonts and matches the wallpaper.
The wallpaper was created by/at: digitalblasphemy.com and it's under their licensing terms. The wallpaper can be found here: