It hasn't been released yet. Nothing but speculation at this point.
My guess is they'll go all-the-way with a Linux base, including the Linux hardware drivers (those work, by-the-way) and there chrome applications. I see it like this, you turn on your PC and go straight to the Internet bypassing the Desktop using the Google OS. Nearly all of us do that anyway or would like to, most of us good straight to our mail when we turn on our PCs. Everything in the Windows OS can be accessed from the taskbar. Looks like Google is side stepping the desktop and moving the taskbar to the top of the Window. Simpler easy, less time consuming then just open applications from there.
The Internet is such a low level application these days it's almost a joke, it's becoming an antique relic that runs at a nails pace, uses few PC resources and an intermittent connection. The high end these days are the virtual world communities, Second Life being there flag ship. Virtual Worlds are so far ahead of the Internet it pathetic.