Red Hat: no desktop products coming

libc isn't going to break, full stop.

However, what *is* a concern is a more general case of something which we 
did see in the last major upgrade. Remember the wtmp format change? 
Remember the GCC exception-handler errors, back when libgcc was always 
statically linked? This is a special case of a more general problem, which 
is that if some library code manages some shared resource, and more than 
one variety of it gets to run in the same address space (as happens with 
static linking, and with differing-soname shared linking), and those 
varieties have different expectations of some shared resource, things will 
break.

Unix doesn't really have a good answer to this other than `soname breaks 
that affect shared libraries that are linked both into libraries and into 
the users of those libraries should force relinking of all those libraries 
at once, or changes of the intermediate libraries' sonames', both of which 
avoid having multiple copies of different versions of the same shared 
libraries in the same address space at once.

Neither of these situations are exactly ideal, but as far as I know 
nobody's thought of a better way. (Has anyone?)