On Fri, 17 Dec 1999 19:27:56 -0500 (EST) 
 woods@most.weird.com (Greg A. Woods) wrote:

 > I confess I don't really understand.  And I share MCR's frustration

That seems to be going around.  I suppose we can explain it AGAIN.

 > First off, doe anything prevent any given system from having copies of
 > the old libraries during a transition phase?

Let's see...

Say you have a program foobar, which you can build from source, which
links against libzap.so.0 and libc.so.12.

libzap calls stdio functions.  It is a 3rd party library, and sources
are not available.

You bump the libc to libc.so.13, and you rebuild foobar.

You are now totally pooched.  foobar now depends on libc.so.12 and libc.so.13.

Watch your program fail in spectacular ways.  Or, even worse, watch your
program fail in subtle ways, corrupting data and giving incorrect results
along the way.  Watch users get angry.  Watch planes fall from the sky.
Watch dogs and cats live together.  Divide by zero.  etc.

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>