This happened this morning to my partners Ford KA.
She tried to use the wipers to move snow off the windows, the key here is, if it is the fuse, none of the wipers will work. If you back on still works, then it is a mechanical problem, but if front and rear wipers are not working it will be electrical. For a starter for 10, try the fuse as per Mike Brown's answer (Jan 2010 "15 amp fuse (blue) top row 5th from the left. Fuse box is below and to the right of the steering column.")
I will report back as soon as I have bought this after work.
Matt McLeary, November 2010