Microsoft is expected to release a new build of the technical preview for Windows 10 in the very near future, according to their own words. The only build so far to be released to the public is 9841 but the next iteration will likely be in the 9860 class of releases.
With this new build, Microsoft has polished up the animations that give the OS a more comprehensive feel. When you open a new window, it flies out on to the screen from the icon and when you minimize it, it collapses back in to the icon on the taskbar; the windows kind of a 'pop' affect to them. It is a slick animation and if you have used OS X, it is similar to the one used to collapse windows back in to the dock.
Before the haters start saying this was copied, Windows has always had transitions and the Windows 10 open and close animations are not as dramatic as what you see on Apple's platform. The image at the top of this post is of build 9841 and not of the build where the animations are turned on.
Without a doubt, you can't miss the transitions and frankly, they look quite good. They add a bit more polish to the UI and that makes it feel like a more complete OS. And while we don't have an exact timeline of how soon Microsoft will release these builds to the public, it looks like it will be in the very near future.