Currently, dev-python/python-3.1.3-r1 is stable on a few arches. Python3 has many bugs, is incompatible with a lot of packages and most of the people just don't care about it. And most importantly, its bugs block stabilization of my packages. I'd really appreciate if we could drop stable keywords from that Python3 ebuild. Repoman seems not to complain about any reverse dependencies.
As per discussion in #gentoo-python, we won't be doing this. However, feel free to help us fix bugs in python-3, so this will get better!