Is the availabilty of AppStack reportable?
As far as I'm aware, the only output from it is via 'Export to PDF", at the top of the view. As it mashes together bits from the other modules, the only way you could do something similar is with a fancy SQL/SWQL query harnessing custom properties.
I just had a look at the current Orion demo site and couldn't see anything under reports which jumped out at me either.. perhaps you have a feature request idea there!
Shame because the product looks like a move to building service models i.e. that server and that application forms a components of that service but without availability reporting it is a bit pointless in my environments.