You're looking at a page with some LilyPond samples. These files are also included in the distribution. The output is completely generated from the .ly source file, without any further touch up.
The PostScript files were generated using TeX and dvips at 600 dpi. The pictures are 90 dpi anti-aliased snapshots of the printed output. The images are in PNG format, and should be viewable with any current browser.
If you want a better impression of the appearance, do print out one of the postscript files.
This page is for LilyPond-2.0.1 (stable-branch).