To properly close this thread:
This seems to have been caused by a problem with pango (ie. NOT A
LILYPOND PROBLEM!) which had been built against Apple's X11, but
subsequently Xorg's X11 had been installed on the machine.
The solution was to rebuild pango:
fink rebuild pango1-xft2-ft219 pango1-xf
I was able to build it and install it, but when I try to run it:
-bash-3.00$ lilypond test.ly
dyld: lilypond can't open library: /usr/X11R6/lib/libexpat.1.dylib (No
such file or directory, errno = 2)
Trace/BPT trap
-bash-3.00$ lilypond --version
dyld: lilypond can't open library: /usr/X11R6/lib/li