A new and very interesting feature taking shape in next major release of Microsoft SQL Server, currently titled "Denali", is contained databases.
Contained databases are based on seperation of database application from instance or management level functionality. This allows for some interesting uses in infrastructaure management, such as database development and release, security management and disaster recovery. Partial decoupling of database entities from instance level entities allows for a more granular approach to application to database mapping. We have very specific method of creating and mapping a user connection using either authentication model (e.g. SQL Server, Windows) and bypass instance level security functions, providing partially self-contained database deployment. As databases are being developed and deployed between environments, management around instance deployment, access and orphaned users is reduced or simplified, as database security meta data are held within the database. This feature provides for a level of portability between different instances\environments, thus a potentially simplified method of propogating databases throughout environments.
Database disaster recovery processes look to benefit from introduction of contained databases. Contained databases provide another method for protecting our SQL Server environments, but increase the security management We can create a DR server hosting a number of contained "mirrored" databases. This strategy provides for a rapid application database recovery process, as data and security contained in database mirror copy.
Very good feature and looking forward to further developments with Contained Databases in future.