You can turn it off, as has been said above.
If it has a mode-2 (which I think that lens has) then you can switch the lens to remove shake only in the up-down direction. So you can switch it to that mode if you are hand-holding the lens.
If you have one of the much newer IS systems, you can still use it on a tripod. I know I do. The only time I've ever had trouble with IS was when I was testing my lens indoors, taking a picture of a lens test chart. The camera was so steady that the IS system was confused... the image in the view finder was sliding to the upper right. It was really weird.
Personally, I've taken pictures in mode 1 (removing shake in all directions) while on a tripod and never had it cause a problem that I've noticed.