There are some really great entries appearing on the SQL Server 2005 Best Practices website. I just noticed this web page which discusses, amongs other things, some new features in SP2 like the vardecimal storage format and LOGON triggers. Take a look:

Top 10 Hidden Gems in SQL Server 2005 http://www.microsoft.com/technet/prodtechnol/sql/bestpractice/gems-top-10.mspx.

I also like the SQL Server 2005 Script Repository