You really can run some KDE4 applications in Windows. It is very great 
Still it is not final version so not all programs work, but Konqueror works nice, but slow.
Anyway currently this is not a shell replacement but just a possibility to run some KDE4 applications in Windows, which is nice. But it is not integrated with Windows, so it is not so usable now.
Waiting for KDE4 shell replacement.
P.S.
As like in Linux it takes a lot of memory 
