Using this, the stylus will apparently be used to control phone functions like music playback and the camera shutter - all from the button, which the S Pen has had for several years.
We say this is strange, because until now the Note smartphone has managed just fine with a 'dumb' stylus - in other words, one which did not connect to the phone in any way, other than through touching its nib against the display.
The prolific leaker, who has been accurate about smartphone gossip in the past, tweeted on July 1: "The Galaxy Note 9 S Pen can be used to control long-range selfie-timer, control music playback, because it is a Bluetooth device, it will do something, unrelated to the pen."
Although Samsung's Note 9 cards are still close to its chest, invitations to the launch event feature a close-up shot of what looks like the S Pen's button, giving this claim some credence.
The Galaxy Note9 SPen can be used to control long-range self-timer, control music playback, because it is a Bluetooth device, it will do something unrelated to the pen. pic.twitter.com/WPS83xUskq — Ice universe (@UniverseIce) July 1, 2018
Being Bluetooth, the S Pen will need to be powered and charged in some way. Currently, the stylus gets its power from an electromagnetic field created by the phone, which gives the stylus enough power to function when it is held close to the screen.
Although low-energy Bluetooth devices can last a long time without charging - think months rather than days - the battery will likely add size, weight and complexity to the simple stylus.
We can see camera control with the stylus being useful, especially when holding a large phone like the Galaxy Note aloft for a group selfie, then stretching to tap the shutter icon, can be precarious. Holding the phone in one outstretched hand and firing the camera with the stylus in the other makes a lot of sense.
For now, all the stylus button does on the Galaxy Note 8 is launch Samsung's Air Command control panel, which offers app-specific controls for the stylus.
Music playback control seems less useful, but we are still curious to see what Samsung has up its sleeve for the Note 9 on August 9.