it's been a long time since I was actively contributing to Lilypond documentation but I have been lurking and following certain threads in the dev mailing list. I'm still around but it still have wrist problems, helped quite a bit by some pretty cool Linux speech recognition software developed by a friend of mine.
I wanted to send a brief note of thanks to everyone who has done so much for Lilypond development. Recently I've been working on a major project, which is to take a public domain counterpoint textbook and overhaul it for use as an electronic textbook. It is done in responsive, mobile-friendly HTML (there will also be an epub version) and I'm using Lilypond to typeset the musical examples. Not only will there be images of all the examples, but I also wrote a bash script that uses Lilypond's midi output to generate mp3 and ogg files for html5 audio players. Finally a music theory textbook where you can click to play the examples instead of having to find a keyboard! You can see the LilyPond source code for any example simply by clicking on the image.
I'm very happy with how it is turning out so far, and constantly amazed at what is possible with lilypond. If you would like to see the work in progress, follow this link.
It will probably be quite some time before I'm done with all of the examples, but I plan to use the textbook when I teach counterpoint again next spring. My current students have been very enthusiastic as I showed them the progress I've made so far.
Best wishes to all, and thanks again for a most excellent tool.