Is there at present a database evolutions tool similar to migrations in RoR?

For those that are unfamiliar, this system:

o Defines initial tables o Subsequent changes to the tables (i.e. drop/add a column/new table) are are then defined and have a version number associated to each change. Undo changes also defined for each step o Command-line tool then can be used to move from one version of the database schema to the next by iterating up/down through the steps