Gmail style blog/chat?

What I'm needing is setup sort of like Gmail

The main post is always at the top and comments or replys are listed under it seperately. But the whole thing is always expanded, never a collapsed view, and only viewable with password

I want it to be sort of SQL/PHP based if possible.

Does anyone know of software like that already made or am I gonna have to write it myself?

Looking for the easy way out rather than having to write it all custom

Thanks