When I upgraded from GNOME 2.6 to GNOME 2.8, gnome-system-monitor and multiload-applet didn't link to the correct libgtop. The libgtop that was installed along with GNOME 2.8 is libgtop-2.0.so.4, and these binaries were looking for libgtop-2.0.so.2. libgtop-2.0.so.2 is the libgtop version that comes with the libgtop-2.6.0 ebuild. Unfortunately I'm not able to redo the upgrade process, but I suspect that this is because "emerge gnome" emerged gnome-system-monitor and gnome-applets before it emerged libgtop. Thus they were linked against the older binary version, and then libgtop was emerged so that libgtop-2.0.so.2 was replaced by the .4 binver. Since the gnome-system-monitor and gnome-applets ebuilds DEPEND on >=libgtop-2.5.2, I guess this is a qualified guess. I would provide a patch, but I don't know how to fix this -- I'm guessing that the DEPENDency should not just be changed to >=libgtop-2.8.0, which is the only way I know to fix it.
although in theory the dep is unneeded sharp i agree its better to avoid these possible problems as much as we can (although fxing the deps up isnt foolproof in the long run either). fixed applets & g-s-m thnx for the report