Yes, simple enough to do once the hardware is corrected; the turn signal switch needs to be a momentary contact but after that, it is all sensors and code. Three axis accelerators are cheap and very effective, and MCU's are all over the place for, as you mentioned, pennies. The code starts off looking like it will be pricey but as always it becomes cheap if it can be spread out across a lot of units, and a turn signal system is something that would work on any motorcycle, regardless of model, brand or anything else.
And using accelerometers it becomes easy to get a handle on all parameters of the bikes' behavior such as sitting at a light: no accel / decel, no speed and the turn signal can stay on for as long as needed, waiting for the rotation (the turn) combined with acceleration. It becomes very easy to map exactly what behavior to look for and when to cancel the signal.
As a no- cost extra, a sudden, near- ninety degree rotation about the yaw axis followed by a sharp decel to [no speed] and this controller could snap on all four signal lights as an emergency flasher.... 'cause the bike just fell over.
Sort of the thinking man's tip over sensor..... well, not really a thinking man perhaps, maybe more like the almost- sober man.
"Honest officer, it was a sudden gust of gravity, I swear!".
Brian
Looks like this STS system uses an IMU (inertial measurement unit) with some algorithms to detect the maneuver. More and more bikes are getting IMU's for things like cornering ABS, traction control and cornering lighting. My Ducati MS has an IMU and the new FJR does as well. This seems like it would be a low cost add to any bike that already has one. Just software. And the MEMS chips needed for an IMU are dirt cheap now. Literally pennies. What a great idea.