Microsoft released a new white paper about database mirroring with MOSS 2007 and WSS v3.0. The key point is that you need to perform some actions when a failover happens. You can do these actions manually or implement them using some scripts. You will also have to do some monitoring to know when a failover has happened.
If you are planning to use database mirroring with SharePoint, all I can say is test, test, test!!!



