sql_migrations produces SQL dumps of ActiveRecord migrations so a DBA can review and execute SQL, which is required in many environments.
ActiveRecord is designed with an assumption that the developer will have many of the responsibilities of a database administrator, so the assumption that developers can execute their own database changes breaks down when using corporate databases tended by professional DBAs. DBAs speak SQL, not Ruby, so there's a need to render migrations to SQL for their review and use.
The first release is a Rails plugin that dumps forward migrations to a file with few other features. There are many features that could be added to this base given demand.
Please use the issue tracker to request additional features that would be useful for you, as well as any defects.