Powerfail confusion

[Tom Horsley]

If I plug in the usb cable for my APC Back-UPS system,
I do indeed see the battery icon in a gnome session,
so it is clear that something is talking to it.

Is that something smart enough to cleanly shutdown the
system on a power failure? Or do I need extra software
like NUT or apcupsd? (I'd kinda rather not answer this
question via the obvious experiment :-).