When asked by Google, it said that Mac and Linux versions are in development and will be released soon.
But the great news is that the folks at CodeWeavers.com have already created a Linux and Mac port of Google Chrome open source code base, Chromium and released it for free.
Chromium on Ubuntu Linux
Chromium on Mac OS X
Available for download on Mac OS X and runs Windows version of Google Chrome as a native Mac or Ubuntu, as standard Linux packages.