This has been an ask from the community for a long time now. We just launched SQL Server 2008 R2 Best Practices Analyzer. The SQL Server rules are executed using the Microsoft Baseline Configuration Analyzer framework. The rules are all Powershell based. So you need Powershell 2.0 and MBCA 2.0 to use SQL Server 2008 R2 BPA. This version of BPA has an extensive set of rules which can validate a lot of commonly known issues in areas like SQL Setup, Engine, Replication etc. This makes the work of a DBA much easier. Another cool feature about this tool is that you can run remote scans also against other SQL instances.
Addendum: April 13th, 2011
Note: It works with SQL Server 2008 and SQL Server 2008 R2.
For the original SQL Server 2008, which BPA should we use, if any?
It works with SQL Server 2008 and SQL Server 2008 R2. I just added this to the original post as well. SQL Server 2008 and SQL Server 2008 R2 are two different releases of SQL Server.