I woudl like to see the IOC engine to be replaceable.
This is quite easy to do by creating an interface and implementation.
Normally its just called IOC.
This would allow the Castle IOC to be used, and hence use NHibernate and the other Facilities and Services that Castle.
It shoudl be quite easy to do i think, because Castle does not depend on the Windows .NET stack specicalised aspects i believe.