These ebuilds come from http://github.com/sjnewbury/multilib-overlay.
If you have some problems, go to the official site first.
libgdiplus : Library for using System.Drawing with mono ( http://www.mono-project.com )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a multilib
For Paludis use this rsync : rsync://gentoo.zugaina.org/multilib-portage
If you have a problem : ycarus(-at-)zugaina.org