I go out of my way to avoid as much silicone as I can. Way down the list in body stuff I can tolerate but I am super careful about combing the ingredient list of anything I put on my face. It's almost impossible to avoid silicone in drugstore skincare though. I mostly have to hit the healthfood store.
Most of the new foundations and other non-powder make-up products are loaded with silicone. I know lots of people love that they blend well and what not but my skin just can't breathe under all that crap. I stick to natural moisturizers and mineral make-up.
If you don't break out, you might be fine with silicone products. I have fairly sensitive skin and find that silicone tends to break me out somethin' fierce. Especially the eeevil -xane 'cones. *shudder*