What is SQL Server "Denali"? What's new?

The new features include :

• Multi-Subnet Failover Clustering
• Programming Enhancements including sequences, ad-hoc query paging and full-text search tweaks
• BI and Web Development Environment Improvements
• Web-based Visualization
• Data Quality Services enhanced

You can view the detailed review here : New Features Of Denali

"Denali" is a code name. Here is the list of the code name of other versions of SQL Server:

• 1993 – SQL Server 4.21 for Windows NT
• 1995 – SQL Server 6.0, codenamed SQL95
• 1996 – SQL Server 6.5, codenamed Hydra
• 1999 – SQL Server 7.0, codenamed Sphinx
• 1999 – SQL Server 7.0 OLAP, codenamed Plato
• 2000 – SQL Server 2000 32-bit, codenamed Shiloh (version 8.0)
• 2003 – SQL Server 2000 64-bit, codenamed Liberty
• 2005 – SQL Server 2005, codenamed Yukon (version 9.0)
• 2008 – SQL Server 2008, codenamed Katmai (version 10.0)
• 2010 – SQL Server 2008 R2, Codenamed Kilimanjaro (aka KJ)
• 2011 – SQL Server 2012, Codenamed Denali

AlwaysOn High Availability and Disaster Recovery

If you're interested in the extra disaster recovery stuff that is included with Denali, there was a useful series of articles on Microsoft's CSS blog:

http://blogs.msdn.com/b/psssql/archive/tags/alwayson/

Additional resources:

• SQL Server AlwaysOn Team Blog
• Brent Ozar's introduction to AlwaysOn

LAG and LEAD (Blog article) and the other OVER clause (MSDN) stuff.

And these blog articles cover most of them