Changes are coming for Chrome users who are running Mac OS X Leopard. According to reports in Ars Technica and CNET, Google is dropping support for OS X 10.5 with Chrome version 22.0.1201.0, which is now available in Chrome's developer channel. This version will make its way eventually into the public arena in the next few months. At that point, Leopard users will be stuck at the most recent version of Chrome.
With Mountain Lion coming out later this month, now might be a good time for users to look into upgrading their OS if their hardware supports it (see Apple's Mountain Lion upgrade page) or start shopping for the new Mac hardware. I hear the new Retina Mac Book Pros are really nice.