At this website you can find a comprehensive study on schema evolution carried out by UCLA and Politecnico di Milano DB researchers.

Among other things there is a precise analysis of the DB schema evolution in Wikipedia. The Wikipedia query workload, schemas and data are available for your tests.

Furthermore, there are a couple of systems supporting schema evolution.
The more relevant tool features are:
- predictability of the data migration
- automatic impact analysis on queries
- tracking of the schema evolution history
- automatic query adaptation (the system automatically rewrite queries to fit the new schema!)
- SQL script generation (for data migration)
- automatic view generation to support old schema versions over the current DB

There is also an on-line DEMO of the tool.
Video Screencast available.