I read many blogs about creating the boot disc after downloading the image from the App store. However none of them seemed to work for me until I found a post on the Mac Dev forums. He are my instructions that worked for me. I was already running Mavericks as my OS.
Also, to get the latest full image update, you can get it from the App Store by going to Purchases and then pressing download as per below.
The 8 GB USB drive should be called Untitled and formatted as Mac OS Extended (Journaled). The installer should be called Install OS X Mavericks.app and should be in your Applications folder.
Run this in terminal and wait about 20 minutes:
sudo /Applications/Install OS X Mavericks.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install OS X Mavericks.app –nointeraction
You should see something like this:
Erasing Disk: 0%… 10%… 20%… 100%…
Copying installer files to disk…
Making disk bootable…
Copying boot files…
You can then boot up from the USB by holding down the option key, then install the GM from the USB.
This is probably going to be the same for the public release.
Note that this will also install a recovery partition.