In most cases it will be safe to use a swiffer on a laminate floor. The only time that I wouldnt recommend it is when you have a smooth finish lamiante with a glossy finish. In this case there is a chance that the laminate will show minor surface scratching. If your laminate is like most and has a texture to it, you will be fine.
One other word of caution is the moisture that you use for the Swiffer. BE careful not to allow exessive moisture on the floor. Depending on the quality of your lamiante, moisture (even a little) can do significant damage. Higher end, moisture resistant laminates would be fine with a damp (lightly) mop or a swiffer.
When it comes to laminate and moisture, always try and dry the surface immediately to ensure a long lasting product.