Preface: I am not a DBA. I'm a software developer, document imaging architect, build system and continuous integration implementer. I use databases to store, query, and retrieve information, and I'm a bigot against stored procedures (unless used as a performance enhancement tool with a non-sproc version already implemented, or it really is too complicated to do outside a sproc).
For those curious, I promised several people I would write up an open-source Data Profiler comparison blog, but I do not feel confident I have put in enough time for this yet.
Open Source Database Change Management
There isn't a lot out there.
http://code.google.com/p/dbdeploy/ - LGPL
http://www.liquibase.org/ - LGPL
http://opendbcopy.sourceforge.net/ - INACTIVE
edit: http://www.sql-workbench.net/ - WbSchemaDiff, WbDataDiff commandline
One of the wishlist items here: http://dhartford.blogspot.com/2008/11/all-i-want-for-christmas-2008-full.html
* Both the active are full featured.
* Both will handle change management well.
* Liquibase seems to have a larger integration-point base (maven, eclipse, etc)
* Neither have an adequate/sufficient UI that would be considered 'quality and usable by a DBA/non-programmer'. Yes, I'm a programmer, but I don't want to program EVERYTHING unless there is a reason for flexibility/customizability.
That's about all I have to say about this subject. The commercial tools still have a strong presence here (i.e. RedGate), as there aren't many alternatives.
For now, I still use old school database viewer/sql tools to extract the DDL and data value changes. The tool I use a lot is http://www.sql-workbench.net/ for this functionality, but I do hope for the above to mature and improve.