I have a working ZM based on Postgres that will be coming out when I get time (the same codebase, you choose the DB at build time). It seems to be pretty much all there except that it's taken off an old branch so the work is just in merging all the changes together and converting new features to be PG compatible.
I haven't done any speed comparisons or anything so I'm not even sure how useful it might be, I've had to do some bodges with PG that might mean it's not working entirely optimally at the moment
Phil
