Take a look at Camelot. Camelot is an OpenSource "Database Frontend Development Framework", is cross platform and based on the Qt libraries and developed using the Python bindings.
There is a also a commercial license available. Camelot aims at the ease of use of Filemaker Pro without the hassles of Access. There are currently very professional applications successfully in production in the industry. I stumbled over it at the european Python Conference "EuroPython" in Florence this year, where the core developers gave a talk. The video is available.
Homepage:
http://www.python-camelot.com/
including viedo tutorials
Usergroup Mailinglist
http://groups.google.com/group/project-camelot?hl=en