Sonic, the image that was posted awhile ago is fake, but this story here is true.
The current builds are nothing more than Vista, albeit stripped down a little.
They've never wrote any of their kernels from scratch. The kernel they're still using is a modified version of the one they purchased long, long ago. This kernel goes all the way back to the beginning. It's been updated, and more and more bloat added to it. The Windows API we use to write interfaces with is still done the same way it was in Windows 95. So what they're planning to do with this one is strip the kernel down. This new kernel is titled MinWin or branded as that so far. It's a very interesting process and kernel.
Anyway, like everyone else said, this version is so far away from release that any changes are still going to look like Vista from the outside.
Here's an excellent article on MinWin.
Paul Thurrott's SuperSite for Windows: Inside Windows 7 MinWin "MinWin/7 is a more sophisticated approach to carving off a bottom chunk of Windows. Here, Microsoft identified that bottom chunk, called MinWin, by performing an automated analysis of all of Windows and figuring out what the dependencies were between the binaries. Any binaries that were considered part of MinWin, were refactored (or split) to remove those upward dependencies. So while Server Core has cyclic dependencies--i.e. connections to pieces of unused components from the rest of Windows--MinWin/7 is self-contained. That is, no code in MinWin depends on anything outside of MinWin."