I am usually only running stable Gentoo systems, so I have not seen the problem myself. However, unstable (~arch) users may be affected and it seems really serious. If you are using prelink and ~arch Gentoo, please read the following before updating and consider undoing the prelinking and removing prelink:
http://bugs.gentoo.org/show_bug.cgi?id=353814
http://forums.gentoo.org/viewtopic-t-863297-start-0-postdays-0-postorder-asc-highlight-.html