Hi, I've just been bitten by this * surprise *
After upgrading to gcc-4.5.4 (from 4.5.3)some packages / ebuilds fail since gcc-4.5.4 doesn't include the libffi.so.4 library.
I had to rebuild dev-lang/perl (all versions here 2.7 3.2) dev-libs/gobject-introspection dev-libs/gobject-introspection-common and I'm not sure that's enough. Unfortunately, revdep-rebuild doesn't fix the problems.The problem didn't occur on a system where I'm using gcc-4.6.x as standard compiler.
Helmut.