Geneology: GEDCOM and PostgreSQL

I am getting interested in creating a web application for collaberativly
compiling family trees. Of course this is not a new idea, but I can't find
much good open-source code about, and I don't trust any of the existing
services not to go bust.

My first task is to build a solid data model.

GEDCOM[1] is a data exchange format developed by the Mormons (who consider
genealogy to be a 'religious obligation'[2]). Together with it's XML
translation GedML[3], GEDCOM seems to summerise the standard data model
which is used by genealogists.

I have a few questions:

Has anyone produced an Postgres-style SQL translation of the GEDCOM
data model?

Are there any existing Postgres-based genealogical tools?

Is there anything I should know about Postgres's handling of the
inevitable tree traversal queries? (Is there anything like the Oracle
connect by syntax?)

[1] http://www.gendex.com/gedcom55/55gctoc.htm
[2] http://www.zdnet.com/devhead/stories/articles/0,4413,2264378,00.html
[3] http://users.iclway.co.uk/mhkay/gedml/index.html

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Cheers

Chris