The APU hotfire test seems to be carried out right now. The rotating service structure (RSS) has just moved to parking position. The hotfire test was originally scheduled for immediately after space shuttle Discovery’s rollout to the pad, but had to be postponed due to bad weather at Kennedy Space Center. It was re-scheduled post FRR, which is today.
There was some discussion whether or not NASA would do this test (there seems to be no hard requirement), but it now seems to be done.