I was under the car today when I noticed there are rubber cylinders in my front springs. Thought that was a little odd, but considering how much I know, I consulted my Haynes book, and nothing is mentioned. I'm about to replace the springs (might now turn into a whole front end rebuild), and I don't know if these are needed. I'll get pics tomorrow if I can find my camera.
My guess is that they are travel limiters, so the spring doesn't slam against itself.
They are there to reduce NVH ([SIZE=-1]Noise, Vibration, and Harshness)[/SIZE]
Keeps the springs from going boi-oi-oi-oi-oi-oi-oi-oing.
Have a look at the rears. You should have some there too.
Sounds like they are staying.