Online check-in, which travelers practically take for granted in their airline travels, is rolling out in the hotel arena. Carlson Hotels Worldwide started offering online check-in to guests staying at Radisson Hotels & Resorts in the Americas in September, and in October Hilton Hotels Corp. launched the service for members of its frequent guest program at select hotels in all its brands. Guest are able to choose their rooms and print confirmations, and in theory, key cards and registration packets are waiting for guests when they arrive.