It's not covered officially, like windshield wiper blades, oil is considered a consumable. High volume M dealerships usually cover it, unfortunately mine is not one and they don't. But I keep 3 quarts in my garage at all time just in case, always good to have. Also my dealership is a good 40 minutes away from me, so like someone mentioned above its easier just to do it myself (not to mention faster). I will say though, it would be nice if they offered it, I am likely going to buy another BMW in the future, and a gesture such as being willing to top off the oil for free would be something that would bring me back to that dealership to buy my next car. Ah well...
Word of advice - if doing it yourself watch the seal on the cap, the o-ring easily sticks when the cap is being taken off then can get bunched when putting it back which will have you spraying oil all over your engine once you start the car, so make sure you examine the o-ring and put a light coat of oil on it prior to putting the cap back on. And also, never put more than 1/2 quart in at a time. In my car once I get 1q low, 1/2q is enough to get me to "max." Man what I would give for a dip stick.
"This is like having a house-cat thatís a bengal tiger." - Todd Deeken, everydaydriver.com, on owning an e90 m3.