Starting point for learning about using databases from Python.
Relational Databases
Relational databases are the most widely used type of database, storing information as tables containing a number of rows.
ChoosingDatabase -- lists databases supported by Python libraries.
DatabaseInterfaces -- another list of databases accessible from Python. (Should merge this list with the above one...)
The DB-API
The DB-API is a specification for a common interface to relational databases. The current version of the specification is version 2.0.
[http://www.python.org/dev/peps/pep-0249/ PEP 249: Python Database API Specification v2.0].
[http://initd.org/pub/software/psycopg/dbapi20programming.pdf DB-API how-to] (PDF).
Future development
DbApi3 -- discussion of possible topics for a DB-API 3.
Historical development
[http://www.python.org/dev/peps/pep-0248/ PEP 248: Python Database API Specification v1.0].
Related tools
HigherLevelDatabaseProgramming -- wrappers that provide simpler or higher-level database interfaces, such as object/relational mappers and SQL generators.
[http://sqlrelay.sourceforge.net/ 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.
Other resources
DatabaseBooks -- lists a few recommended titles for learning about databases. These books aren't Python-specific.
[http://dmoz.org/Computers/Programming/Databases/ Programming:Databases] category on dmoz.org
Non-relational Databases
PersistenceTools -- describes non-relational tools for storing data on disk.
[http://www.matisse.com/product_information/language_bindings/lang_python.html Matisse Software] provides Python bindings for their object database.