It's new to 2005, and though it's not turned on by default, it damn well should be as it is in Oracle and Postgres. Multi version concurrency control (i.e. writers not blocking readers) is old hat in the db field. Prior to 05, you just liberally sprinkled (nolock) on your selects and accepted that you may get a dirty read but that it was better than the db falling over with over aggressive locking.