Mac OS X is Unix with a pretty face. That means most of the things available for Linux systems are also available for Mac's. Most of the tools, practices, etc transfer pretty easily. Since most web hosting providers use Linux systems, this makes Apple's Mac a great choice for prototyping web sites, especially as Apple includes a web server bundled with the system.
Unfortunately Apple did not include enough for this to be a great prototyping system.
Fortunately there are some simple things you can do which adapts Apple's Mac so it is a great web site prototyping platform. Further, you can use a Mac as a production web server if you like.