When the database gateway components were refactored support for each database had to be reimplemented. Postgres and Oracle are still in need of attention; ie. they are not supported in 7.x
Implementing Postgres support is very likely straightforward, however, Daemon no longer has any Postgres clients and so it has not been a priority for us. If anyone would like to have a crack at Postgres support (or even fund Postgres support) we'd be very happy to assist.