One thing we've regularly needed to do is to load and save objects to multiple data sources. One example where this might apply is when your security objects (users, roles etc) are stored in a separate database to your application database. Another example is where you have application data and user preference data - the application data being stored to a centralised database and the user preferences being stored to a local xml file, and you would like a unified interface where you simply save objects and have them go wherever they should.

In Habanero 2.3.2 this can be achieved with a DataAccessorMultiSource.  Here is an example: