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Current Version: 2006.1
Editions: x86, PPC etc.
Core: kernel 2.6.17, xorg 7.1
Package management system: Portage
Price: Free (as in beer)
Gentoo is a Linux distribution that is a hair's breadth away from Linux From Scratch in the respect that almost everything you install will be compiled from source, specifically for your machine.
With Gentoo all applications are installed using Portage, the Gentoo package management system. Portage removes dependency hell entirely; it will sort out all the dependancies for any package you with to install.
Gentoo is highly internet based. Only a small 65MB download is required to get the absolute base system installed. From then on all packages are taken from the online Portage tree when required.
bluemonki: I run Gentoo on my main computer and on my Apple iBook, it's so nice and easy to administer and look after with Portage making everything a breeze. The only downside being that the installation is relatively painful and it can take about 3 days of compilation before you get a graphical system up and running. But I'm informed that they are currently writing a graphical installer to make this much easier.
prawnstar: I used Gentoo on a mix of computers (Sun Sparc, Intel P3, XBOX, and Athlon), while it's true that it can take 3 days to get a working GUI, you don't need to start from stage 1 (as Bluemonki must have), you can start from a stage 3, and they also have binary packages too. It's a steep learning curve, but what you learn can be applied to any other distribution, well worth a try!