Gentoo eudev is being developed since for the past several months udev has been integrated within systemd and this is resulting in a poor situation for Gentoo developers with increased breakage and a dependence upon systemd. "The systemd developers are uninterested in providing full support in udev to systemd alternatives. These are problems for us and we have decided to fork udev to address them."
While eudev is being developed within the Gentoo camp, other Linux distributions are free to deploy eudev too within their systems. The primary goal of eudev is explained as "[addressing] the problems with systemd-udev that caused us to fork it in the first place. In particular, we want better compatibility with existing software such as OpenRC and Upstart, older kernels, various toolchains and anything else required by users and various distributions. We also want to minimize regressions and work with developers of other distributions (and components used by them) to address issues."
The eudev developers may look at making it boot faster as well, they have already rewritten the build system and restored support for older Linux kernels going back to Linux 2.6.31, and there is a Beta 1 release plus is already available from the Gentoo Portage tree. Gentoo developers are also working on introducing uclibc support, regression fixes, and other features.
More details on this udev fork can be found from the Gentoo eudev announcement.