> BTW, I use FEATURES=buildpkg, so after initial compile, switching glibcs
> back to the old gentoo approved 2.3.5-rX compiled with a gentoo approved
> gcc-3.4.4, is simply a matter of emerge -K-ing the desired glibc.  That's
> really the only reason I'm daring enough to be running the still
> hard-masked snapshot in the first place.  With emerge -K, it's almost as
> simple as a glibc-config, parallel to gcc-config, would be, and in some
> ways less problematic, given the fact that since I've compiled KDE against
> gcc-4's libstdc++, every time I gcc-config back to 3.4.x, certain KDE apps
> (generally, anything using khtml, so not only Konqueror, but kweather,
> and a few others) refuse to work correctly, until I gcc-config back to a
> gcc-4.x once again.

Yeah... uh... that's a known PITA issue...  HOPEFULLY everything
compiled against the 3.4 libstdc++ should work with the 4.0 libstdc++.
You can get around this particular issue by
creating /etc/env.d/01usegcc4stdcpp to force the loader to use the gcc4
libs:
LDPATH=/usr/lib/gcc/x86_64-pc-linux-gnu/4.0.1:/usr/lib/gcc/x86_64-pc-linux-gnu/4.0.1/32

Then run env-update

You can check that it's using the gcc4 libstdc++ by doing:
ldd /usr/kde/3.4/bin/konqueror | grep stdc++