AppOfflineTemplate not working in WD 3.0 RTW

The help documentation for "-enableRule:AppOffline" has this to say:

msdeploy -help -enableRule:AppOffline:

Takes an ASP.NET application offline by placing an app_offline.htm file in the root directory of a site or app before a sync begins.  The file will then be removed upon successful completion of the sync.

Example(s):

    msdeploy.exe -verb:sync -source:iisApp=siteName, -dest:iisApp=siteName,computerName=MyComputer,AppOfflineTemplate=template.htm -enableRule:AppOffline

However, actually attempting to provide the AppOfflineTemplate setting errors with the following output:

msdeploy.exe -verb:sync -source:iisApp=SourceWebsite -dest:iisApp=TargetWebsite,AppOfflineTemplate=app_offline_template.htm -enableRule:AppOffline:

Error: The provider 'iisApp' does not support the 'AppOfflineTemplate' setting. Supported settings are (SkipAppCreation, managedRuntimeVersion, enable32BitAppOnWin64, managedPipelineMode, authType, computerName, encryptPassword, includeAcls, password, prefetchPayload, userName, wmsvc).

If I poke around in System.Web.Deployment I can see that the template is supported by the rule, but based on the errror message it looks like it wasn't hooked up properly. 

Is this something that has simply been pushed to a future release?