A source based distribution located on http://www.gentoo.org very much inspired by the way they to things in *BSD.
Did have a reputation of being very bleeding edge for developers, but is not as up to date on tcl and tk as a developer would like.
If you have root access on your Gentoo machine you can more or less easy integrate new packages by making your own ebuild file and place it somewhere where portage can find it, but not mess with it.
2006-04-07, SB: Got frustrated that many of the packages that ActiveTCL provide does not have an ebuild for Gentoo. The uttermost frust was to face the fact that tkcon is not a part of standard Gentoo. More to come.