KDE 4 on Windows! A mini graphical installer pulls configuration files and packages from the net, so you can always get the latest versions of software without having to update the whole lot in one fell swoop.
That's the ultimate goal, anyway, but as you'd expect, there are still some glitches to fixed. Nonetheless, KDE's Holger Schroder demonstrated some of the biggest KDE apps running impressively well on Windows, including Konqueror, Kate, and this map program (I forget the name - doh!).
Currently, the main goal is to just get KDE programs running smoothly on Windows -- the team doesn't plan to make it a complete desktop replacement. So we won't see Plasma on Windows for some time (if ever).
A Gentoo Portage-based build and package system will be available for developers, and on the whole, it's looking very good indeed. Hopefully we'll soon have another great way to introduce Free Software to Windows users.