Today is a hodge podge of facts about mirroring, since I am in learning mode I thought I would share with you.

• Mirroring is deprecated, meaning it is going away and moving to AlwaysOn availability groups.  Now is probably not the time to devise a mirroring plan.
• You can mirror some or all of your databases on a particular instance.
• You can only mirror databases in the FULL recovery model.
• Mirroring supports only one principal and one mirror.
• All versions support witness modes but only Enterprise supports high-performance mode.
• Enterprise, Standard and the new BI version all support the high-safety mode.
• You cannot mirror a database that is using FILESTREAM file groups.
• You can only mirror user databases.

Enjoy!