Google has released the AdWords API Local Database Sync project. The scripts that make up the project can be used to schedule reports using the AdWords API, store the results in a local database (using SQLite), and then run queries against the database. The AdWords API team says that this would make querying a local database faster and more cost effective.
The scripts are written in Python, and make use of the SOAPpy libraries for accessing the AdWords API SOAP service. The Python code is written against the dbapi2 database API, and by default it will use the SQLite implementation and store the report data in a SQLite database file on the local file system. It's possible to swap out the SQLite libraries for another database library that supports the dbapi2 interface, informed Jeffrey Posnick.
More info: AdWords API Local Database Sync