Starting point for learning about using databases from Python.
Relational databases are the most widely used type of database, storing information as tables containing a number of rows.
DatabaseInterfaces -- List of available Python databases interfaces. This also helps you choose the right database for your application.
The DB-API is a specification for a common interface to relational databases. The current version of the specification is version 2.0.
Slides: Datenbankprogrammierung mit dem Python Database API (in German)
DbApi3 -- discussion of possible topics for a DB-API 3.
HigherLevelDatabaseProgramming -- wrappers that provide simpler or higher-level database interfaces, such as object/relational mappers and SQL generators.
SQL Relay is a persistent database connection pooling, proxying and load balancing system for Unix systems, supporting many different databases and languages, including PostgreSQL and Python.
DatabaseBooks -- lists a few recommended titles for learning about databases. These books aren't Python-specific.
Programming:Databases category on dmoz.org
PersistenceTools -- describes non-relational tools for storing data on disk.
Matisse Software provides Python bindings for their object database.