[jpitz]

You cant do that, without a large effort in music education or ensembles of all electronic instruments implementing this feature. Everyone else will be out of tune.

Edit: you could do it, but you'd better implement it on a feedback system that can re-tune in a hundred milliseconds or so.

[BurningFrog]

I'm just talking about an individual keyboard, though if all instruments are digital, which is pretty common these days, you could have a whole orchestra dynamically adjusting pitch to make "perfect" harmonies.

What I wonder is mostly if that would sound any better.