Yes, lot's of great stuff out there.
What makes embedding (of some sort) attractive is formatted documents. LaTex
and other *Tex will do this. Emacs is not designed for this.
If one likes to manually insert TeX commands using a text editor (such as
emacs), why not manually insert LilyPond entities and markup as well? If one
wishes to work in a previewed mode, Frescobaldi (and Lied) can do Lilypond
nicely. Oolilypond let's one do such very nicely from openoffice. However,
this is more programming than scoring. More oriented towards singe-stave,
exercises and such and full composition/notation.
If one wants to work with a fully formatted document and edit score in a
normal MIDI/graphical manner as well, one can cut and paste images from nted
or mscore into openoffice quite nicely. The one thing this closed-
source/microsoft thing gives one is integration. The big bullies as M$soft
spent millions on research showing that folk will fork up dough for such
convenience. I am not promoting this, just informing and hoping to spark a few
ideas :-)