anyone heard of "recall"?

Here's an interesting approach to redundancy - I wonder how much of a
performance hit postgres would take if it optionally used this for
underlying table storage?
    http://www.fault-tolerant.org/recall/recall-faq.html

Browsing through the cvs tree, I even see a postgres directory -
apparently they're doing some work on exactly this idea, and have run
into some stumbling blocks. I know that replication questions and
RFEs pop up frequently on this list - maybe this'll provide a
solution for some folks.

-- Mike