As pop mentioned, SPOPS is moving along. PostgreSQL support will be in the next version (0.40) which should be released today or tomorrow (June 9-10). I've been using it for a month or so and it's given me no problems. It also supports Sybase ASE/ASA and MS SQL Server (thru DBD::ODBC on Win32). Other database support probably isn't that difficult -- the main differences are auto-generating primary keys and ensuring that the DBD driver supports datatype value binding.
One of the features of SPOPS (and Class::DBI AFAIK) is that you can retrofit an object representation to existing data. That is: you don't need to modify your schema to use SPOPS. Accessing legacy data is a major strength of Perl, and this makes it easier...
Chris
M-x auto-bs-mode