Database Mirroring will be disabled in SQL Server 2005 RTM
Database mirroring in SQL Server 2005 will be turned off for the RTM.
One of the things we learned is that we believe our Database Mirroring feature needs more time in the hands of customers before we make it generally available for production use. The feature is complete, has passed extensive internal testing, and we are committed to making it generally available in the first half of 2006. We will continue to field test the feature with customers and will release it for general use as soon as you tell us it is ready.
We also heard from many of you that you wanted a more seamless management experience across all SQL Server 2005 editions. With this in mind, we are in the process of building a scaled down version of our SQL Server 2005 Management Studio for SQL Server 2005 Express Edition. We believe this will provide you with the ability to more efficiently manage SQL Server 2005 Express Edition with increased automation and lower complexity. The final delivery of this technology will also depend on additional feedback from customers, but we anticipate that it too will be delivered in the first half of 2006.
I guess we will have to wait for it :(
ps you can enable it if you want with a trace flag but it won't be supported.