Is there data visualisation tool for postgresql which is capable of displaying inter schema relations as well?
I don't think there is one for PG (though I think that pgAdmin will have something like this in the future).

If I need visualization of PostgreSQL data schema, I use the MySQL Workbench (I know, I wil burn in hell for this...). This works pretty good, though i throws some errors with SQL not known to MySQL (though this does not stop the process on the first error, it continues). This worked pretty well for me in the past.

Be warned though: many of the features only work with MySQL somewhere in the back or SQL generated by/for MySQL. This is only usefull if you want plain visualization.