After downloading this ISO (the Developer Preview is only 629MB), the image can be burned to a disc and immediately booted. Project Indiana incorporates a "Slim Install" LiveCD for x86 systems. Just like Ubuntu, Fedora Live, and a number of other Linux distributions, you can boot to this CD and start using it without ever touching the contents of your hard drive.
Once inside the LiveCD environment, you can opt to install it to a hard drive via the Caiman graphical installer. Ian Murdock and company have reached these download / installation improvements in the first milestone and it's truly a great experience. Project Indiana doesn't have anything like Ubuntu's Bullet-Proof-X or any added features to ensure a straightforward and easy install process if you run into hiccups along the way, but when it comes to the installer, it's now a first-rate experience and something familiar to Linux users.
In our initial tests, the LiveCD Caiman installer had worked great and is almost comparable to Ubuntu's Ubiquity installer aside from the Migration Assistant support and other small details that can be improved (such as using a map for selecting the time zone as opposed to three drop down menus).