Three key points from the document:
1. SQL Server 2005 introduces several new high availability and scalability features such as database mirroring and partitioning to protect against server failures and reduce database contention.
2. Database snapshots can be used to protect applications and users from errors by providing historical, read-only views of databases.
3. Optimistic concurrency controls and online index operations in SQL Server 2005 allow databases to remain available for reads and writes during maintenance operations.