Vertica is another case of an analytics focused platform that dirived from Postgres, version 8.0 IIRC.
FWIW,
You might be thinking of Greenplum, and I think it forked from pg 8.1. Vertica was built from scratch, it is not using Postgres as the basis for the db. This is according to the engineers that I have spoken to in the past at Vertica. I believe there was some code ported over for their command line client "vsql", but I could be wrong about that. At the very least, vsql looks and acts like psql from a user's point of view.
I agree absolutely with you about the dazzling speed of certain types of queries -- one of my tests was a simple aggregate query (a bunch of SUM() and GROUP BY's) over about 500M rows and it returned results in a handful of seconds. The same query in our Postgresql server with 2x the number of disks took handfuls of minutes IIRC. On the flip side, I found some of the complex Window functions performed on par or better in Postgresql than in Vertica.
