I think you've gone a bit far there Fungers - surely there is a distinct difference between a soul and an identity. As I was taught it, the soul is what survives us when we die, and goes to Heaven (or not). That's not synonymous with an identity in my book. Obviously I reject the notion of the soul entirely (what with there being absolutely no reason to believe any such thing exists) but I had to quibble with you there.
I'd like to chuck in an old thought of mine at this point. Some while ago, while musing on the sort of biological/technological crossovers Mr Koo raises above, I began to wonder about the religious implications of al this. I was raised as a Catholic, and taught very early on - indeed, the first two Q&A's of the catechism:
Who made you?
God made me.
Why did God make you?
God made me to know Him, love Him, and serve Him in this world, and to be happy with Him forever in the next.
But what if we reach a point where death is no longer mandatory? It'd be nice to imagine that those old SF cliches will come true, and we'll one day be able to either upload our minds into a mainframe when our bodies give up, or that medicine will advance so far that our bodies will live forever. At that point, what do we do about Heaven? If one is a believer but is suddenly faced with the option to avoid death, how many would have the courage to elect to die in order to meet their God and get their eternal reward? And what would God's view of all this be, if he is suddenly cut off from His supply of souls joining him every day? Would there be great wrath brought down upon the Earth?
Be honest, religious folk - you get the choice to die and face Judgment at the hands of your God, or to live here on Earth forever but never see God in the face. What do you do?
An entertaining afterthought - perhaps this is how the Christian rapture will come about. All the faithful will choose to die, so that the Earth is left populated only by atheists and agnostics. And Buddhists.