Recently we got the sad news that chromium-browser has been dropped from Debian Squezze. The problem is that the upstream moves very fast, and that includes WebKit, which makes backporting security patches very hard. Oh, and it's going to move even faster.
Well, Gentoo has hit some problems too, see bug #335750. Hopefully we will manage to stabilize the 6.x series, and prepare for the 7.x.
In case you'd like to help, see the project page. Will Gentoo be fast enough for Chromium?