New thread, now that we've got RTM...
I installed RTM via a Technet sub. On retail Win 8, if you have a dual display setup, hitting the Windows key pulls up Metro only on the secondary display. This mitigates the pain quite a bit.
EDIT: OK, not quite. I was still on first boot, and although I selected a monitor as my primary, apparently Metro* didn't wise up to this fact until the first reboot. So Metro does only appear on one screen, and it's the primary display. That blows. I could reverse displays so Metro would appear on the 'secondary' that I use for chat/mail, less frequently used apps, but then my games would launch over there as well. If you could choose the display Metro appears upon, it'd be far less onerous.
*UI formerly known as Metro.
Re-EDIT!: Windows-Page Up or Windows-Page Down will toggle the Start screen to another display without changing your primary screen. So, back to things being not so bad.