I've got folding plastic pedals on my dahon ciao, but they don't seem to make much of a difference in terms of saving space.

I've mks detachables on my dahon mu sl and they're much better for grip and making a true difference to the size.

If you're in the UK you can get MKS pedals from:

http://www.foldingbikes.co.uk/accessories_pedals.htm