Thanks to mdiegi and atolboo for the replies.
Well, with the intention of installing yawp as suggested by mdiegi I deleted pyplasma-weather. When I did this, the crashing stopped.
So, it seems, that on my machine at least, this particular widget is not a happy widget.
However, I was unable to install yawp as it seems I don't have the repo for it.
The video posted by mdiegi is impressive and this is exactly what I want. However, don't I already have kwin as part of KDE4.2? So, how do I get the rotating cube?
All that I have is a lot of transparency and some very stuttering wobbly windows which do not at all wobble smoothly like they do in Ubuntu with compiz-fusion.