The drop shadows in 3.1 are great, but at 1600x1200 resolution, they were a little 'thin'. So I patched kdelibs/kdefx/kstyle.cpp to increase the depth of the shadow from 4 pixels to 8 pixels.
To apply the patch:
patch kstyle.cpp < kdelibs.kdefx.kstyle.cpp.patch
This was done on FreeBSD. I hope it works for your platform. I can't see any reason why it shouldn't.