Cobb reveals to Ariadne that he knows inception is possible because he did it to his wife. He implanted the idea that "the world she is living in is not real," allowing them both to escape the deepest subconscious. The idea grew, causing her to kill herself in real life. Cobb talks to Saito, now an old man, in the deepest layer of subconscious and reminds him about their arrangement. Saito reaches for his gun. Cobb wakes up, passes through customs and meets his father. He goes home and sees his kids' faces. The last shot is of Cobb's totem, the spinning top... either spinning forever which means he's in a dream or about to topple which means he's in reality...
Count3D
Answer: The answer above is solid and I agree, but there's another plausible way of looking at it. It is implied at the end that Cobb could still be dreaming (we never see if the top stops spinning). If that's the case, then he would likely dream his children to be exactly how he remembers them.
jshy7979