Southwest Airlines still serves peanuts, but will advise the boarding agents of (that) flight to suspend the sale of peanuts. Southwest also encourages all passengers with food allergies to book a flight early in the morning due to cleaning schedules.
Delta and Northwest Airlines have not eliminated peanut products, but do offer a buffer zone. The zone requires the passengers of three rows in front and three rows behind to not have any peanut products or be served peanut products during the flight.
American Airlines serves no peanut products in flight, but may serve products with other nut ingredients. Also the snacks they do serve, even though they may be peanut free, be sure to read the label because it could say "may contain traces of peanuts", or "processed on a plant that also processes peanuts".
We pack our own snacks and then we don't have to worry about it.