Google has posted a link to a beta version of Gears for Safari: http://dl.google.com/gears/current/gears-osx-opt.dmg. The minimum system requirements are: Safari 3.1.1 on Tiger 10.4.11 or Leopard 10.5.3, although Gears is likely to support other WebKit-based browsers in the future.
“This is BETA, it is not an official release, it might break your browser. Chances are it will break your browser. Please proceed with caution,” warns Jeremy Moskovich from Google.
If you find bugs, post them at Google Code. The list of issues includes interesting details about the upcoming offline version of Gmail: “After viewing Install offline access for Google.com Mail, I click Next and the installer window disappears. Is it telling me that initialization is not needed? Hard to say. It appears that I now have an Offline settings tab, so I guess it is initialized.”
Source:→ Google System