I suspect a lot of the people who visit this site are experimenting with pre-release copies of Windows 8. Microsoft has made the Windows Developer Preview available for free download, but the download is in a disk image (ISO) file.
So what do you do with an ISO file? You can’t use it directly to install Windows; instead, you have to burn the image to a DVD or copy it to a bootable USB flash drive. Although there are plenty of utilities to help you accomplish this task, the easiest of all is Microsoft’s Windows 7 USB/DVD Download Tool. It was designed for use with Windows 7 images downloaded from the Microsoft Store, but it works just fine with Windows 8.
You can get this tool from a variety of sources:
Download and install the utility on any PC running Windows 7 (32-bit or 64-bit), Windows Vista, or Windows XP SP2 or later.
For the x86 and x64 ISO files without developer tools, you’ll need a blank DVD or a completely empty USB flash drive of 4GB or larger. At 4.8 GB, the x64 version with developer tools is too large to fit on a regular DVD, you’ll need a dual-layer DVD (and compatible drive) or an empty 8GB (or larger) flash drive.
Update: As a reader thoughtfully points out, the bootable flash drive will work fine on PCs that use a conventional BIOS. That’s the overwhelming majority of PCs sold today. However, if the design of your PC uses Unified Extensible Firmware Interface (UEFI), this utility won’t help. UEFI-based systems will be much more common when Windows 8 ships, but they’re rare today.
Open the utility and follow the four simple steps. This step allows you to choose whether you want to burn the ISO file to a DVD or copy the files to a bootable USB flash drive.
This is what you’ll see if you choose the USB device option. Select the correct drive and click Begin Copying.
The entire operation doesn’t take long and requires no user intervention. When you’re finished, you have a DVD or a flash drive that you can set as the startup device on your computer so that you can begin a clean setup. Or you can open the setup disk in Windows Explorer and double-click Setup to upgrade your current Windows installation.
Ed Bott 
I used my old standby method for creating a USB install stick.
First, launch CMD.exe with administrator rights.
1. diskpart
2. select disk 9 (or whatever the number of that disk is, use ‘list disk’ to find it)
3. clean
4. create partition primary
5. select partition 1
6. active
7. format fs=fat32 quick
8. assign
9. exit
Then use 7-zip to extract the .ISO file to the USB stick.
I believe this method will work on UEFI systems. I’ll have to test it…
Scott, I’ll be very interestred in hearing your results with this technique on a UEFI system. Thanks!
The only UEFI system I had available was a Mac. The USB would need to be formatted for a Mac to boot, so that won’t work. I’m in a sea of Dell’s otherwise, so no go there (yet, Dell says they will go UEFI soon.) Everything I’m reading about USB booting in UEFI says it should work, if allowed by the system and setup properly. Big “ifs”… The more I read about UEFI, the more I dislike it. 😦