some are.
your body requires salts, which are commonly refered to as electrolytes. that's also why a sodium free diet is a bad idea. if you have been to a hospital, or watched some hospital show, the saline solution commonly used in iv drips is a salt solution which matches your blood's characteristics.
certain sports drinks (gatorade for example) contains electrolytes. drinking this water will help your body absorb the water faster, i do not have exact details. but i will say this, all else the same, drinking 32 oz of gatorade will also mean you pee faster than drinking 32oz of water. ;-) and as mentioned above, some sports drinks have too much sugar, which is not a really good thing unless you need it. some drinks also have vitamins and minerals.
another note on water: your body cannot absorb distilled water (pure water). drinking it is no way to keep yourself hydrated.