There is a known bug/issue with Kopete where Kopete wants to compile with webcam support and there is no option to disable this. This issue prevented one of my KDE meta packages from installing.

The work around, enforce opengl USE flags for x11-libs/qt through /etc/portage/package.use making sure there are no other entries for qt (mine had 3!). Recompile qt by doing emerge qt kdelib. Don't do an emerge --upgrade for qt and kdelib as this won't force a full recompilation and all should be well.