there are a couple of references in the book where it seems like toru didn't commit suicide, the first being where he describes "a dozen years laters" he felt like bursting into years when he realized Hitsumi's (spelling ?) sadness...having read the wind-up chronicle a few months back, where the ending was very confusing. I think Norweign Wood be fitting if it had a nice ending where like a previous mentioned that Toru realizes that he is in the world of love after he calls Midori, which makes sense to why in the beginning of the book they show him that he is now forgeting Noako. Ofcourse there is still the possibility that he is following Noako's love and memories and as the beginning of the book mentions he is slowly forgetting her, because he realizes that she never loved him.
In my opinion this is probably the best book Murakami's I have read so far, even though I have only read three, Kafka on the Shore, Wind-up Bird Chronicle, and Norweign Wood, and now starting on Wild Sheep Chase and Hardboiled-egg....good times...good times..