Can Sakai be installed on Mac OS X?

Yes, Sakai can be installed on Mac OS X.

Many Sakai developers develop on Macs. Some of Unicon's own developers have installed Sakai on Mac OS X laptops for development purposes and Zach Thomas (of Aeroplane Software, with whom Unicon has had the pleasure of collaborating on numerous projects) also prefers his MacBook Pro for his development needs. (He's posted several getting started with Sakai training screencasts that happen to use Mac OS X as the development environment demonstrated.)

Sakai technically can be installed onto and served from Mac OS X Server servers in production. Of the 192 registered Sakai deployments, 2 report using Mac OS X server in their Sakai deployment environments (including Cambridge). Unicon doesn't recommend using Mac OS X and XServe hardware to serve the Sakai application and attendant architecture, simply because it seems to introduce needless expense, will make a Sakai deployment needlessly different from its peers, and Mac OS X Server is not one of the server OS platforms on which the Sakai Foundation QAs the Sakai software. That said, in principle, there's no reason you couldn't successfully run the Sakai software on Mac OS X servers.

There's nothing special about installing Sakai on Mac OS X beyond all the normal special things about running Java on Mac OS X (or anywhere else, for that matter). To run Sakai, you'll need a working JVM / JRE. You'll need to configure the classpath properly.