..should be appearing very soon for download. I can see it in Windows Update so it will hopefully be appearing here http://technet.microsoft.com/en-gb/sqlserver/bb428874.aspx shortly.
...ends on April 8th 2008 so I would recommend upgrading to service pack 2 (and the latest cumulative hotfix package) as soon as possible. SQL Server service pack support is documented on the lifecycle website here http://support.microsoft.com/gp/lifesupsps#Servers
I'm currently working with a customer who had a requirement to backup the mirror database. You may wonder why they want to do this - there are a number of reasons which I won't go into right now. The simple answer is that it is not possible to backup the mirror database as it is in a recovering state. It is not even possible to use any SAN-based solution to take a clone/snap due to the same reasons. What I mean by this is that whilst it may be possible, it will not be supported and the database consistency cannot be guaranteed.
Maybe a feature request for Katmai+1?
I haven't blogged for quite a while now... and my excuse? - there is not enough time in the day! One thing that I have managed to do is schedule a trip to Manchester this Thursday (29th November) to talk to anyone interested about SQL Server 2008 https://msevents.microsoft.com/cui/EventDetail.aspx?culture=en-GB&eventid=1032355918. It should be good as I haven't been to a Technet event for quite a while.