From the following article on mirrored backups: http://www.sqlservercentral.com/columnists/awarren/2990.asp
SQL 2005 gives the added capability to backup to two locations at once.
backup database adventureworks to disk='c:\advtest3.bak'
mirror to disk='\\train4\backup\advtest3.bak' with format, description='test'
Both backups are done at the same time cutting the overall backup time.
If one of the backups fail both fail.
It is not part of the standard maintenance plan.
