Prevayler - orthogonal Persistence..

I noticed this Slashdot | Prevayler Quietly Reaches 2.0 Alpha, Bye RDBMS? today after my previous post about data impedance. If you cut away the hype there might be something here.

Another similar solution I am playing with just now is db40 which is a Java and .Net object database. It is very elegant and easy to use.