On 7th of October Alvaro Herrera committed his own patch, which adds quite interesting possibilty:
Log Message: ----------- Make it possibly to specify GUC params per user and per database. Create a new catalog pg_db_role_setting where they are now stored, and better encapsulate the code that deals with settings into its realm. The old datconfig and rolconfig columns are removed. psql has gained a \drds command to display the settings. Backwards compatibility warning: while the backwards-compatible system views still have the config columns, they no longer completely represent the configuration for a user or database. Catalog version bumped.