Hello,
This is just a brief note to let you know I am using Magma as a backend for an education application of interactive exercise for primary schools. Magma is used to record all the student achievements. It is still in active development stage and stuff can be look at http://www.istoa.net (only in French but Google will translate it easily in English). Nothing usable for end users.
The OO nature of the Magma persistency is very important as it greatly enhance the abstraction level of the persisted data (no flat data but living instances). Basicly I record in Magma the exercice instances of the student (and some more), but also EventRecord so the whole student activity can be replayed. The OO level just greatly help to persist a wide range of exercices instance without to worry about the specific interactive nature of the exercices (the benefice is huge)
Part of the application is also using Seaside so the teacher can review the student achievement. In the Seaside application a squeak plugin with Magma is used to replay the student activity directly from the browser.
All in all, Magma is nice, but I fell that ODB require more carefull design compare to RDB. So more attention is required but the reward is hudge ;-)
Hilaire Fernandes