I got LilyPond working in a mediawiki page using the lilypond mediawiki extension. Although, I had to tweak the extension code and I may have goofed something up.
All of time images being rendered from the <lilypond> and <lilybook> elements have a lot of whitespace. I'm using that lilypond is rendering to an image based on the paper size. I'd like to have lilypond remove the extra whitespace from the output image so that it takes less room on the wiki page. Here is the wiki page I'm working on: