see: http://www.accellera.org/downloads/standards/systemc/
In the tree. Thanks for pointing it out. +*systemc-2.3.1 (10 Aug 2014) + + 10 Aug 2014; Thomas Beierlein <tomjbe@gentoo.org> +systemc-2.3.1.ebuild: + Version bump (bug #508568). Thanks Jeremiah +