Thanks Simone, I did not know that. The Airplay name that is displayed on iTunes must be constructed using the string "Shairport on " + hostname, correct?
May I suggest that having independent host and Airplay names would be more flexible.
Airplay speakers are often named by location for example "Studio Speakers", "Bedroom Stereo", etc., or by type for example "B&W A5 Speaker", "Zeppelin Air", etc. This makes it easy to identify the speakers in the Airplay list on iTunes.
In my case, I currently have two Pi's whose hostnames are RP1 and RP2, and whose Airplay names are "Studio HS5 Monitors", and "Bedroom Stereo".
A field for the Airplay name could be placed near the on/off button for the service

Regards,
tc-fi