grid things and postgres

Hi,
I am working on the G System project (BSD licenced) and we are going to
be (eventually) implementing a distributed database to hold data for the
game that (eventually) will be developed. People have (though I don't
think anyone has seriously investigated yet) suggested that we use a
grid with postgresql databases to serve the data. There will also be
processing of data, so it's not just a distributed database, I guess.
The idea is to have a virtual reality universe (GUniverse) that is able
to evolve. It is going to be along the lines of a MMORPG (or whatever),
but not only can you get new guns, you can also develop them using
resources, have hurricanes, whatever. Ideas are still fairly nebulous as
you can see!
My understanding is that (grid) machines will probably take over
management of certain parts of the universe, and so people (cities,
countries, etc) will be managed by different servers. When you go from
one to another you would be passed over. There would also be events that
might effect more than one person (city, country, etc) so would need to
be able to be spread, etc. There would also be things that applied to
the whole system. What exactly is handled by client and server is for
the future.

Does this sound like a job for globusTK? I read a bit about clusgres but
it is not OSS.

I realise that I don't have a clue but would like some ideas on how to
get one! Does this sound like something postgresql might be at home
with? Am I talking about a grid or nothing of the sort? I saw that
oracle 10g has "grid" capabilities but aside from being out of the
question, I don't think it would do what we wanted anyway.

Please excuse the waffley nature of this post.
Cheers
Antoine
ps. I think the devs are mainly C++ but as far as I could see java has a
head start in terms of grids and it wouldn't be out of the question.