The 1.x series of docker cannot be installed in Funtoo because of a missing dependency on lxc-1.x.

i7 ~ # emerge '=app-emulation/docker-1.0.1' -a

These are the packages that would be merged, in order:

Calculating dependencies... done!

emerge: there are no ebuilds to satisfy ">=app-emulation/lxc-1.0".
(dependency required by "app-emulation/docker-1.0.1[lxc]" [ebuild])
(dependency required by "=app-emulation/docker-1.0.1" [argument])
i7 ~ # ls /usr/portage/app-emulation/lxc/
Manifest files lxc-0.8.0-r1.ebuild lxc-0.8.0_rc2-r1.ebuild metadata.xml
i7 ~ #

This has been the situation for awhile now.

Why are the lxc-1.* ebuilds missing from Funtoo? Gentoo has both lxc-1.0.3 and lxc-1.0.4 ebuilds available in portage.