With the hard feature freeze for KDE 4.10 having been this past week, a number of KWin window manager improvements were merged just in time.
On Martin Gräßlin's blog, the KDE KWin maintainer, writes
about some of the improvements.
Among the recently merged KWin 4.10 items are the merging of AppMenu support for having window menus inside the window decoration, the initial port from Xlib to XCB, the color correction GSoC work, a performance improvement for moving windows in a composited environment, and window decoration improvements.
Overall it's looking like the next KDE release will be another nice upgrade for the KWin window manager.