It's hard to totally disprove these first Chrome OS shots, though there are plenty of reasons to be suspicious. Setting our skepticism aside for a second, here's what alleged leakster allegedly saw, allegedly. Update: Proven fake.
As an employee of a parts supplier for Acer, one of Google partners for Chrome OS (true!), he was privy to a brief demonstration of a Private Developer Beta. They showed a full installation, which took about 10 minutes. After installation was done, desktop to desktop reboot took about 25 seconds.
As for the desktop, it is minimalist: at the bottom of the screen is the Chrome Bar, which is the system's dock, start menu, or whatever you'd like to call it. The glowing blue icon, which looks like the center of the Chrome logo (also true!), opens the main menu, and hides when not in use. It can be activated with the Windows key, a la the Start Menu, though Chrome-loaded netbooks could well have a dedicated Google key, or Chrome key. Update: The creator of these screenshots has admitted that they're fake.
Now, some reasons to be suspicious: these shots come a little soon for my comfort, just one day after the announcement; the shots could easily be mocked up in an existing Linux desktop environment (this one looks a bit like XFCE, actually); the shots don't necessarily look like they were taken in an Acer conference room (floral table tiles? really?); and, most damningly, the colors in the word "Google" are ordered incorrectly. Lastly, the demo was carried out on a Acer Extensa 4620Z—not a netbook, which would accord with Google's stated first target for the OS. So.
But you can see the same evidence I can, and the description in the leak is quite long, so just have a look for yourself—I'm just not overly hopeful. And anyway, even if this is real, we're just getting a tiny aesthetic preview of an early build of Google's Linux desktop environment, not any meaningful insight into how the OS works, performs or is in any way distinguishable from other existing products. [ChromeOSLeak—Thanks, MC Gamer!]