The SQL Server Books Online documentation on monitoring covers a couple of new topics, and all the old favorites on using System Monitor, SQL Profiler, and SQL Trace. The new monitoring features in SQL Server 2008 are Data Collection and SQL Server Extended Events.
If you've used the SQL Server Performance Dashboard Reports with SQL Server 2005 SP1, you'll find Data Collection in SQL Server 2008 to be like that on steroids.
It provides an extensible framework for collecting data, storing it in a data warehouse, and then building reporting on top of the data warehouse. Rather than being stuck with predefined reports, you have a very comprehensive monitoring framework. One of the other challenges with DMVs, the standard reports, and the Performance Dashboard reports is that they only provide a snapshot of current system execution, so you can't see what happened one second before or how things have changed over the last one second. Data Collection solves that problem because the Management Data Warehouse is now the repository of the data collected.
Previous versions of SQL Server have had several levels of events available to monitor. You had the option of the full set of SQL events in Profiler and SQL Trace, and then there were the notification events, which are a reduced set of events based around DDL type events.
SQL Server 2008 introduces a new event framework — SQL ...