Parallaxing is something I’ve been after doing for a while – because it looks awesome!
I moved the different planes using the Translate function: http://unity3d.com/support/documentation/ScriptReference/Transform.Translate.html
All you need to do is set different speeds for each section.
These are good examples of effective parallaxing: http://www.youtube.com/watch?v=sLNQU5nfQvQ
http://www.youtube.com/watch?v=HXREh5hacV0
I’ll have to try and upload a video of it working on Dream Swing. Getting this done helped me to figure out the scale of the world – I don’t want a big piece of landscape moving in the background – it should be small things like bits of grass etc and the spider should roughly to scale – previously I had a tree that was way out of scale.