Has this type of book already been done?

This morning I got an idea for a book, and I really think I could get pretty far into it. I’ve been thinking I’d submit it to Inkpop if I’m satisfied with it when it’s done (I realize this might not be for years). But I’d hate to get all into it and discover it’s already been done. So this is the basic idea of it:
There are three different people that have a mutual friend that has just died, or maybe is dying.
You’re reading their journals and blogs
They don’t know each other, but towards the end they start to get to know each other and comfort each other as their mutual friend is dying.

So does this ring any bells? If it’s already been done, I’ll probably just write it to get this nagging idea out of my head.