What is the lifetime of an AppDomain in WCF?
Does it relate to InstanceContextMode, ConcurrencyMode and/or AspNetCompatibilityRequirements RequirementsMode?
I'm looking to know how long my static variables will be around and how often they'll have to be recreated.
WCF doesn't actually control the app domain lifetime, the host does. If you're hosting in a Windows Service, then it's the lifetime of the service. If you're hosting in IIS it's the lifetime of the application pool which is subject to all sorts of recycling based on how its configured.