Just to give everyone a quick heads up, the stable request for KDE SC 4.6.2 plus KDEPIM 184.108.40.206 is likely going to be filed soon. On the whole, the upgrade should go very smooth. In case there are problems, we now have a Gentoo KDE 4.4 - 4.6 Upgrade Guide, covering the most frequent issues. In addition, it probably never hurts to look at the general Gentoo KDE Guide.
If you want to test before the actual stabilization takes place, just grab the keyword file... Cheers!