According to Paul Mestemaker, the SQL Server Best Practices Analyzer is no longer being tied to SQL Server Service Pack releases. This announcement is being made in conjunction with the first production release of the tool.
The SQL Server Best Practices Analyzer is a code analysis tool specifically written to warn developers about questionable practices. Some people like to think of them as compiler warnings, errors that can be ignored but probably should not be. .NET programmers have been using a similar tool, FxCop, for a number of years now.
The term 'best practices' itself has always been somewhat questionable. What may seem like a good idea one day may turn out to a horrible idea later due to unforeseen situations and misunderstood interactions. Devising best practices for new products is especially problematic.
While SQL Server 2005 is not exactly new, database migrations can take months or even years of planning. As new companies rollout the new version of SQL Server, new scenarios are encountered and practices have to be refined.
In order to quickly respond to changes in recommendations and best practices, the SQL Server Best Practices Analyzer has been shifted to its own release schedule. Like .NET's FxCOP, new versions of the tools will be released as practices are codified and analysis rules are written.
You can learn more about Microsoft's recommendations for using SQL Server at TechNet.