For those who think it's about Kurt Cobain, it's not:
Eddie Vedder said:
No, that was written when we were on tour in Atlanta. It's not about Kurt. Nothing on the album was written directly about Kurt, and I don't feel like talking about him, because it [might be seen] as exploitation. But I think there might be some things in the lyrics that you could read into and maybe will answer some questions or help you understand the pressures on someone who is on a parallel train.