It's very possible that it is in apposition. However, it does not change the semantic meaning much even if it is. Either way, Jesus is being associated with 'life'. Either directly as 'the life' or indirectly as 'the word of life'. By the grammar and context both are possible, but the traditional understanding does carry some weight in this respect. If the vast majority of commentaries/translations have understand the phrase as 'the word of life', then I would take it that way unless there is very good reason not to. The important thing that we can learn here though is that we shouldn't take the translations as authoritative, and should keep our eyes out for these alternative readings, especially if they change the meaning. An interesting verse is John 2:11 (Ταυτην εποιησεν αρχην των σημειων). I think every translation renders it something like "This first of his signs he did..." although I've heard very good arguments that it should be rendered "He made this the beginning of his signs". This means that John is not focusing on the fact that this was his first sign, but rather that Jesus made it his first sign. It is focusing on his sovereignty and choice as Lord. Basically, it comes down to whether you take ταυτην as being an adjective modifying αρχην or as a stand alone pronoun. Wallace is where I read this, and his argument is very good.
Speech is my hammer, bang the world into shape, now let it fall! -Mos Def