In my previous post on the Government Computer News article about SQL Server 2005, I mentioned that database mirroring was in the RTM version of the product, but that, since it wasn't supported, it required a trace flag to turn it on.  I neglected, however, to give the actual trace flag.  The flag is 1400.

Here is the offiical disclaimer from the online documentation:

Microsoft support policies do not apply to the database mirroring feature in SQL Server 2005. Database mirroring is currently disabled by default, but may be enabled for evaluation purposes only by using trace flag 1400 as a startup parameter. (For more information about trace flags, see Trace Flags (Transact-SQL).) Database mirroring should not be used in production environments, and Microsoft support services will not support databases or applications that use database mirroring. Database mirroring documentation is included in SQL Server 2005 for evaluation purposes only, and the Documentation Policy for SQL Server 2005 Support and Upgrade does not apply to the database mirroring documentation. 

So, if you are interested in evaluating this feature please give it a try and let us know what you think.  Also, for more information on database mirroring, check out the following technet article.

-David