I don't know if I'm the first one to notice this but ShapeShifter and Illustrator CS don't get along in Tiger. If you try to move an already selected anchor point with the Direct Selection Tool (the white arrow on the top right of the tool palette) you end up switching to the application windows that's behind your Illustrator workspace. Same goes with trying to change a bezier curve by draging.

All anchor points in an selected object also becomes transparent. Kind of funky looking but it's not what I'm after

I haven't tried this with any other versions of Illustrator but I made a clean install of the application after upgrading to Tiger.

Might also let you know that I tried it with more than one guiKit.