Nate, OpenERP does have modules that use reporting engine that connects directly to PostgreSQL DB instead of going through OpenERP. jasper_report module provides the integration with Jasper Report (we have modifications made to make it work in 7.0), pentaho_reports module with Pentaho Server.
All direct reporting solutions, in my view, suffers from authorization problem, i.e. the access control list and record rules (and any other security related setting) does not apply. Hence the user running the report may see data that in OpenERP they do not have access to.
Direct reporting solution will open another connection to the database. You need to account for it when configuring PostgreSQL.