If the app is deployed using a non MSI installer, you will need to have a look at the command line parameters and see what it exposes ... or have a dig through the registry and see if you can find a key to check for (unfortunatly it all gets a little messy which is why MSI's appeared ).
OK, I was needing the info in order to implement a Java custom run-time.
And actually, I have dug the registry info by searching for the name displayed in the Control Panel. Well, once again, thank you very much, Neillans!