How does Safari get updated on OS X? How is Safari updated in OS X? I know this seems like a simple question, but I cant find any good documentation on it. I know of a software update tool that would prompt you for updates on windows, but I would like to know how this is currently done on OS X.

The reasoning for my question is I am comparing browser auto-update functionality and am working on documentation to support plans to guarantee certain extents of browser compatibility for a product. The documentation for Safari seems a little lacking so pointers to an authoritative source would be most welcome in addition to an answer from experience.
In OS X, Safari is updated via the normal system bundled software update process. On Lion, this is the Apple Menu, Software Update tool which can be scheduled or disabled.

On Mountain Lion, this function remains in the Apple Menu, but runs through the Mac App Store app

http://www.apple.com/softwareupdate/

In the end, both tools call softwareupdate binary that you can also run from the command line. 

This differs from your Windows experience where the Apple Software Update tool runs to update all Apple software (Safari, QuickTime, iTunes, etc.) since it is not part of Microsoft's software update process.