emerge -auD world
These are the packages that I would merge, in order:
Calculating world dependencies ...done!
[ebuild NS ] kde-base/arts-3.5.0-r1 USE="alsa arts esd mp3 vorbis -artswrappersuid -debug -jack -kdeenablefinal -nas -xinerama"
[ebuild U ] app-text/docbook-xml-dtd-4.1.2-r6 [4.1.2-r5]
[ebuild N ] sys-apps/kudzu-knoppix-1.1.36-r2 USE="nls python -livecd -minimal"
[ebuild U ] mail-client/evolution-2.4.2.1 [2.4.1] USE="-dbus* -mono*"
[ebuild N ] app-text/poppler-bindings-0.5.0 USE="gtk qt -cairo"
[ebuild U ] app-text/evince-0.5.0 [0.4.0-r2] USE="-dbus* -nautilus*"
Do you want me to merge these packages? [Yes/No]