What good are SQL Server schemas?

Schemas logically group tables, procedures, views together. All employee-related objects in the employee schema, etc.

You can also give permissions to just one schema, so that users can only see the schema they have access to and nothing else.

Just like Namespace of C# codes.

They can also provide a kind of naming collision protection for plugin data. For example, the new Change Data Capture feature in SQL Server 2008 puts the tables it uses in a separate cdc schema. This way, they don't have to worry about a naming conflict between a CDC table and a real table used in the database, and for that matter can deliberately shadow the names of the real tables.

I know it's an old thread, but I just looked into schemas myself and think the following could be another good candidate for schema usage:

In a Datawarehouse, with data coming from different sources, you can use a different schema for each source, and then e.g. control access based on the schemas. Also avoids the possible naming collisions between the various source, as another poster replied above.