i used scotchbrite and wd40 on my planer which seemed to do it pretty well. it only had a bit of surface rust from winter time and was a bit grubby. bought it up nicely though.
As suggested, 5 mins with scotch brite and some WD40 will work wonders, wipe down with some rags afterward. An occassional application of paste wax such as Liberon lubricating wax will help work glide over the surfaces and should give some protection against recurrence.
I often end up with glue on mine which I scrape off with an old but sharpened chisel held at as low an angle as possible. It still leaves a stain in the 'grain' of the cast iron though.