Personally I have never used it. I don't put information in a form and then decide everything needs to be cleared. I would edit one field.
Plus cancel in a UI suggests canceling an action which is in progress. Filling a form is not something in progress.
Would a "Clear All" button be more appropriate?
EDIT: (from merged question)
If "reset" buttons are not redundant, then why so? Give me a case where they are completey accepted, useful and maybe even encouraged/required?
If you feel obliged to put one in; does that imply that your form could be more usable?