It can basically do "Query" on anything that can be enumerated. Can generate sets. Compare and mix sets. What else would you expect? If you are asking about CRUD operations on persisted source then that is basically the duty of classes where it feeds the data (ie: Entity Framework, ObjectContext has SaveChanges() method to propagate insertions, deletions and updates to source).

PS: BTW Linq is extensible and already extending (ability to do queries in parallel and distributed are the most striking features from my POV).

>so what else besides getting data out of a database can it do?
>
>Peter