In other discussion about a microkernel, Gary Thorpe noted these historical links about softupdates:

http://www.netbsd.org/Documentation/tune/5.html#a3
http://www.netbsd.org/Documentation/misc/#softdeps
http://www.mckusick.com/softdep/index.html
http://www.usenix.org/publications/library/proceedings/usenix99/mckusick.html

And Pedro Guffuni followed up with this:

http://www.ece.cmu.edu/~ganger/smallfiles.html