Another interesting comparison between in-body stabilization and in-lens is this.
If you really need IS, either for long telephoto lenses and/or slow shutter speeds, the effect through the VF is totally different.
For IS lenses, when IS is turned on, that shaky image in the VF just smooths out very nicely so that you see the effect.
Now I haven't ever held an in-body IS camera, but from what I read (and it makes sense), you never see the IS effect in the VF. You just have to have confidence that it is working and hit the shutter button.
Gene