Hi Paul,
If you create DVD/CD master image with Disk Utility, it will include hybrid HFS+ ISO/Joliet filesystems. This means that your friend can just burn the .dmg file straight to DVD/CD, and it should work fine in his or her computer. But if he or she is a Linux user and is used to mounting .iso images without burning to disc (e.g., loopback device), it may not be as easy as with plain ISO images. If this is a problem, Mac OS X ships with a command-line utility named `hdiutil` which can be probably be used to strip out the HFS+ filesystem, leaving behind a plain ISO image. Alternatively, there is probably some information on the web or at VersionTracker which could assist.
