Kind of a dumb question, but anyway: is Update Service client capable of reporting on an initial install of the software package (not an update)? The package would be Update Service enabled.
To rephrase: I need to track down software installs (on UNIX, so Activation Service does not fly), both initial installs and future updates. I have no doubt that Update Service will report the information I need about updates, but what about initial install?
Your installation and/or software could log an instrumentation item "installed" for example, upon first installation and perform a check for updates.
Have a look at the instrumentation APIs (ie logTransaction()) for further details. They're very open and you can write many pieces of info to them to aid you.
