Good Windows Info: http://cloanto.com/kb/3-157.html
Solid Mac Info: http://www.trah.co.uk/starterfile/mac.htm

Hybrid CDs with Toast
The only thing that Toast allows for you to do is make a CD where users on each platform - Win/Mac or Unix - will only see the files for that suppoorted platform, and none other. Win/Unix utilize ISO 9660. Macs support that format, but use their own individual format too. By using Toast, you can hide these files from other platforms. Other Mac issues, like icons, window position, etc., are also supported with the hybrid format.

One thing to keep in mind is that even without hybrid software, all platforms can 'see' ISO 9660 cds - hybrids just make it prettier and more convenient.

Here's an explanation on hybrid production using Toast from Roxio: http://www.roxio.com/en/support/toast/toasthybrid.jhtml

A Thing About Macs and OS X
Autorun will not work on Mac OS X. According to Autorun-Autoplay-tools.com, " Mac autoplay behavior requires QuickTime 2.0 or above and System 9 or below. OS X does not support autoplay. Classic will autoplay a CD if Classic is already running before the CD is mounted. This would be useful if you're planning a presentation to work over all environments for the Macintosh. A few years ago there was a Mac virus which used the QuickTime Autorun feature to wreak havoc on Mac’s all over the world. Macintosh engineers came up with a solution for fixing the problem—they simply removed the autorun feature from the OS X operating system. Hence the inability for OS X users to autorun CDs."