For users with SMP systems compile speed can sometimes be vastly improved by having MAKEOPTS="-j" in /etc/make.conf This currently breaks the building of some packages, because an object file is not always compiled fully before make tries to link it. I assume that this could be fixed in someway. packages to test this on are lynx and gconf.
If MAKEOPTS breaks an ebuild, then it is a bug. We can tweak the ebuild to not build in parallel. Please report specific instances that fail as individual bugs.