If an application is loosely coupled (if the term is appropriate here) with the database using stored procedures, web services, and meta-data configuration, then even significant changes to the database may not require any changes to the application at all. The application should also be coded to accomodate things like the addition of optional stored procedure parameters or new columns in the resultset without breaking. That's the ideal architecture.

Yes, where I work there are separate teams working on the database changes and application changes; they submit change orders seperately to the production control / DBA team, and database vs. application changes typically get deployed at different times, sometimes even days or weeks apart with no adverse affect on the users.