the directory http://www.kernel.org/pub/linux/kernel/people/geoff/cell/ps3-linux/ does not exist any more. As the directory content is changing rapidly, I suggest linking to http://www.kernel.org/pub/linux/kernel/people/geoff/cell/
Wouldn't it be even better to remove cell-sources from the portage tree? Mainline kernel and gentoo-sources work fine on PS3 nowadays. The outdated PS3 related documentation hanging around causes a lot of problems for the people who are only starting to use linux on PS3. This outdated 'sys-kernel/cell-sources' package is also contributing to the mess.
dropped