Google released Gears for Safari on OS X (minimum requirements are Leopard 10.5.3 or Tiger 10.4.11) that enable you to access all the Gears-enabled sites (such as Zoho office, WordPress, the new YouTube uploader and Google Docs offline) in Safari.
When you install Gears, you'll notice that it's composed of 2 components: an NPAPI plugin which lives in "/Library/Internet Plugins" and an InputManager. Gears needs to load first thing upon browser startup, for cases in which the first page loaded into the browser is from the Gears offline cache. NPAPI provides no mechanism for loading that early (it only provides support for loading plugins the first time a page specifically includes them) so we needed a small InputManager to do the work for us.
For browsers other than Safari that use the WebKit engine, we've provided a really simple mechanism to allow them to load Gears into their program without using the InputManager. Fluid is one example of a 3rd party browser that supports Gears this way.
On the Mac, Gears desktop shortcuts are actually small applications that are designed to open the website in the same browser they were originally created from. This means that if you created them from a Fluid app they'll open in that same place and if you've got multiple versions of Firefox installed on your machine the shortcut will open in the right one.