The service pack 1 for SQL Server 2005 has now gone public. If you have been waiting for Database mirroring then this is the service pack you should be testing.
Also Books online has been updated for this CTP. The services pack has been in private beta for a while now and it’s great to see Microsoft following through with the same level of beta testing as was done for SQL 2005.
Remember the CTP is not a supported release and is for testing purposes only. So the same rules apply to the use of any beta product. Bearing that in mind I would get into testing the CTP soon as possible
Check out: Microsoft SQL Server: SQL Server 2005 SP1 CTP