emerge PEAR-Translation2-2.0.0b9 fails because of a problem on line 59 in php-pear-r1.eclass. The package untars into the directory PEAR-Translation2-2.0.0beta9. The eclass implictly assumes that the directory name is identical to the package name. It is not ("b9" is replaced by "beta9"), so cd ${S} fails. Adding the following just before line 59 if [ "${S}" = "/var/tmp/portage/PEAR-Translation2-2.0.0_beta9/work/Translation2-2.0.0b9" ] ; then S="/var/tmp/portage/PEAR-Translation2-2.0.0_beta9/work/Translation2-2.0.0beta9" fi makes emerge succeed. Of course, this is a kludge, not a good general solution for this type of issue.
Fixed in CVS.