Sounds more like a Fog. Caption says it all... "What you can't see won't hurt you... IT'll Kill You!"

I am awesome!

Plan9 has what's called Venti,

"...Venti, intended for archival data. In this system, a unique hash of a block's contents acts as the block identifier for read and write operations. This approach enforces a write-once policy, preventing accidental or malicious destruction of data. In addition, duplicate copies of a block can be coalesced, reducing the consumption of storage and simplifying the implementation of clients. Venti is a building block for constructing a variety of storage applications such as logical backup, physical backup, and snapshot file systems."

http://plan9.bell-labs.com/sys/doc/venti/venti.html

the points this guy makes make sense, but it seems like he is just asking for the re-creation of USENET