This is a Quartz composer file (installed with developer tools, free), which means you can edit it too if you want.
The file works as advertised and is pleasant enough on the eyes. Not 5 stars as there are better screen savers out there, but it is pretty OK.

@Micro Burst Software: Perhaps you need to developer tools installed, i'm not sure. Worked fine for me and showed up in system prefs when installed to ~/Library/Screen Savers.