>     How are shared libraries implemented in NetBSD/mac68k?

The interface, at least, is modelled on SunOS.  For details, I'm afraid
that the answer is: "RTSL" (Read The Source, Luke).  The interesting
pieces are in src/gnu/usr.bin/ld and src/lib/csu.

>     Are there any recommended books on learning about shared libraries
> and their implementation?

I don't know of any--except the on-line/printed docs for the various
commercial systems that use shared libs.

>     Where can I find how Apple implements shared libraries in the MacOS?

I'm sure they document somewhere--perhaps in updates to IM:Memory.  You
might poke around ftp.info.apple.com.

-allen

-- 
Allen Briggs - end killing - allen.briggs@bev.net ** MacBSD == NetBSD/mac68k **
   Where does all my time go?  <a href="http://www.netbsd.org/">Guess.</a>