- Gentoo Linux - ships stable, beta and dev channels. Security updates are promptly pushed to stable. NaCl (NativeClient) is enabled, although pNaCl (Portable NaCl) is disabled. Up to 23 use_system_... gyp switches are enabled (depending on USE flags).
- Arch Linux - ships stable channel, promptly reacts to security updates. NaCl is enabled, following Gentoo closely - I consider that good, and I'm glad people find that code useful. :) 5 use_system_... gyp switches are enabled. A notable thing is that the PKGBUILD is one of the shortest and simplest among Chromium packages - this seems to follow from The Arch Way. There is also chromium-dev on AUR - it is more heavily based on the Gentoo package, and tracks the upstream dev channel. Uses 19 use_system_... gyp switches.
- FreeBSD / OpenBSD - ship stable channel, and are doing pretty well, especially when taking amount of BSD-specific patching into account. NaCl is disabled.
- ALT Linux - ships stable channel. NaCl seems to be disabled by default, I'm not sure what's actually shipped in compiled package. Uses 11 use_system_... gyp switches.
- Debian - ancient 6.x version in Squeeze, 22.x in sid at the time of this writing. This is two major milestones behind, and is missing security updates. Not recommended at this moment. :( If you are on Debian, my advice is to use Google Chrome, since official debs should work, and monitor state of the open source Chromium package. You can always return to it when it gets updated.
- Fedora - not in official repositories, but Tom "spot" Callaway has an unofficial repo. Note: currently the version in that repo is 23.x, one major version behind on stable. Tom wrote an article in 2009 called Chromium: Why it isn't in Fedora yet as a proper package, so there is definitely an interest to get it packaged for Fedora, which I appreciate. Many of the issues he wrote about are now fixed, and I hope to work on getting the remaining ones fixed. Please stay tuned!
This is not intended to be an exhaustive list. I'm aware of openSUSE packages, there seems to be something happening for Ubuntu, and I've heard of Slackware, Pardus, PCLinuxOS and CentOS packaging. I do not follow these closely enough though to provide a meaningful "review".
Some conclusions: different distros package Chromium differently. Pay attention to the packaging lag: with about 6 weeks upstream release cycle and each major update being a security one, this matters. Support for NativeClient is another point. There are extension and Web Store apps that use it, and when more and more sites start to use it, this will become increasingly important. Then it is interesting why on some distros some bundled libraries are used even though upstream provides an option to use a system library that is known to work on other distros.
Finally, I like how different maintainers look at each other's packages, and how patches and bugs are frequently being sent upstream.