CyberTuner – The $999 iOS Piano Tuning App That's Well Used Amongst Technicians
cybertuner.com
cybertuner.com
Especially the reviewer who mentioned him using an old version of the software running on a PocketPC until it got released on iOS.
Disclaimer: I don't tune/play the piano, just heard from a friend who had a technician at home that used some expensive software on their iPad tune it.
Counter point though - not all tuning is equal. e.g.
Church organs. At the churches I used to attend this was considered a legit risk factor - the people capable of tuning an organ are old, scare, dying & not keen on traveling. What are we gonna do when X dies was a real issue.