Never heard of it ?? Well it is a new feature with 11.2.0.2. You can take your rman back, some nas storage, and open it up for write.. It creates new blocks on write on a NFS mounted device, but it is so cool !! Kind of like a flex clone. Netapp must be a little worried
Here is a little more information on it from an openworld presentation.
Problem
Databases often replicated for test and development
Replicating databases is time-intensive
Requires lots of disk space, even when data stays static
Solution – dNFS CloneDB
Instantaneously replicate your production database for testing, development, reporting
Works for all NAS storage
Data replicated on cloned database only when necessary – when data is modified
Available in 11.2.0.2