When is too young to talk about death?

[totallynaive]

My 2.8yo has just asked his father where heaven is and why do people go there. I think he's probably too young to have to explain this to right now, but it sort-of came up through watching an animation in which a pet died, and then from Pippi Longstocking, which he loves but which has maturer themes very well dealt with in a fun way. I know we'll have to deal with this soonish as my dad is really not well.

He's a bright kid, very sensitive, picks stuff up, has a large vocabulary, and I don't believe in telling white lies to him where unnecessary. It also seems to me that he is logical enough to realise we can't all hang around for ever. Anyone got any good tips for dealing with this question if it turns up again?

There are books you can get that deal with it in an age appropriate manner. DD goes to a children's hospice so children die when she is there. She's been going since she was about 3 or 4 so they have helped with reading these books and dealing with the subject appropriate to understanding and age.
I cant recall any titles mind, sorry.