It seems that the bitcoin ebuild will take a while before it gets into the main tree. So please add the overlay from https://gitorious.org/bitcoin/gentoo into the central repositories.xml. The overlay includes also some other bitcoin and cpu/gpu mining related ebuilds. Reproducible: Always
added
Looks like the wrong URL was placed in the repositories.xml file. It should be git://gitorious.org/bitcoin/gentoo.git instead of git://gitorious.org/bitcoin.git
fixed