Currently, the latest version of dev-libs/xerces-c marked stable (at least for amd64) is 3.0.0-r1. This build is both pleasantly broken (see bug #269659) and contains a security vulnerability (see bug #280613 or http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2009-2625). As a whole, the "stable" ACCEPT_KEYWORDS has had many broken builds lately and it's actually causing me to consider Ubuntu after 4 years with Gentoo. For all architectures where dev-libs/xerces-c 3.0.0 or later is marked stable, please mark version 3.0.0-r1 as stable ASAP. I really feel that it's bad for our stable platform to be broken, requiring googling, researching and adding to package.keywords just to get it to build.
*** This bug has been marked as a duplicate of bug 280613 ***