Read about how to enable trusted computing on Mac OS X. The document’s coverage includes:

A discussion of the TPM hardware present in certain Macintosh computers
Release of an open source TPM driver for Mac OS X
Release of a Mac OS X port of an open source trusted computing software stack
An overview of using the driver and [...]

A discussion on how Apple’s binary protection works in the x86 version of Mac OS X:
Understanding Apple’s Binary Protection in Mac OS X