An interesting change in OS X Snow Leopard is how the installer works. In every previous version of Mac OS X you would boot your computer up using the installer disk and install from it that way. In Snow Leopard that’s not the case anymore. The installer runs directly from the mounted DVD, closes all of your applications and then installs a bunch of files for awhile before rebooting into the installer to finish the job.
That’s interesting because it means the DVD itself is not as central to the process. It is still used in Snow Leopard, but this is a step towards removing that dependency. If the process could be tweaked to boot the system from a specially crafted disk image file, you wouldn’t need the physical media anymore. Operating Systems will certainly be distributed as downloads at some point, but will it be as soon as Mac OS X 10.7?
As a side note, this new install method makes it easy to upgrade a Macbook Air to Snow Leopard. Once you share the DVD from another computer, you’re all set. The Remote Install Mac OS X utility doesn’t have to be running.
Update: I originally thought the install process didn’t boot from the DVD at all, but while doing an update on an iMac I saw that it does indeed! Whoops!