Chrome is available for Windows, Linux and Mac. Its great extensions are available for Windows and Linux versions so far, but Google is planning to send them to Mac soon. I observed different problems for the beta versions (which you must have for extensions), like intense using of resources or unresponsive state, especially on Linux, and in generally after using it continuously for several hours.
Download Chrome (all OS's, Windows stable): http://www.google.com/chrome
Download Chrome (Windows-Beta only): http://www.google.com/intl/en/landing/chrome/beta/