CentOS, Fedora..
Foresight Linux is starting to become my favorite distro. The only downside is there is just not much documentation on it, since its new, and theres not a big community built around it (yet).
Its built from rPath linux. rPath is a company founded by quite a few original key Red Hat engineers/people.
They basically had the task of building a new linux package manager from scratch, and came up with Conary. Its a very fine grained incremental package manager and revision control all in one. Its pretty damn amazing, and takes all the advantages of the different pacakges managers out there, and puts them all together, along with some new bells and whistles.
Foresight to rPath, kind of what Fedora is to Red Hat. Check it out.
http://www.foresightlinux.org/