Apple has released source code for the open source Darwin project. Darwin is the open source kernel on which Mac OS X is built. The company has released source code for versions 6.7 and 6.8, which correspond to Mac OS X 10.2.7 and 10.2.8 respectively. The short note from Apple (that says roughly we said above):
Darwin 6.7 and 6.8 Source Code Posted
The Darwin team is pleased to announce the availability of the source code for Darwin 6.7 and Darwin 6.8. These sources correspond to Mac OS X 10.2.7 and Mac OS X 10.2.8, respectively, and are available via the web.
Note that as of this writing, Mac OS X 10.2.8 has been pulled by Apple, though the links to the corresponding Darwin source code are still active. You can find the download links at Appleis Darwin Web site.