Betanews has taken a first look at WindowBlinds 5. One of the most obvious new features in WindowBlinds 5 is its ability to do per-pixel alpha blending on nearly all of your Windows GUI controls including the title bar and borders of your windows. This allows for all kinds of new skinning effects (not to mention making it much easier to create cool looking themes). One popular effect that we're seeing are people making skins that make Windows XP appear similar to Microsoft's upcoming Windows Vista OS.
Windows Vista is a huge step forward for Windows. Its experience is delivered through a composited 3D accelerated surface. Or put another way, the Windows Vista environment will have the same capabilities that a modern PC game would have and all the effects there-in.
Needless to say, Windows XP lacks this, but in terms of user interface, Stardock was able to develop a technique that allows WindowBlinds to leverage the advancements in video cards over the past few years so that Windows XP could superficially look similar to Windows Vista. It should be pointed out that Windows Vista is much much more than just a visual overhaul. It really is a next-generation OS that Stardock will be encouraging users to move to as soon as it's available.
Hopefully WindowBlinds 5 will help users get a taste of the kinds of cool things one can expect in the future in Windows itself.