dev-lang/swig 3.0.0 was released on 2014-03-16. It completes support for C++11, go 1.3, python 3.3. On my system (amd64) the package merged by just renaming the 2.0.12 ebuild appropriately.
2014/06/04 - SWIG-3.0.2 released
This release has been made to fix a bug during installation, but it also includes a couple of other rather minor changes.
Added to the tree.