Equal Temperament.........or not?

[casioman]

Have concerts been given where pianos have been tuned to other scales?

[allthumbspiano]

Would there be a need unless it is non-western music?  Can't the piano player just go to whatever key they want?

[silverwoodpianos]

A temperament is not a scale; it is how the musical scale in the whole keyboard is set according to a mathematical calculation.

 Perhaps the information you were looking for was have any concerts been performed using Victorian temperaments or early temperaments for harpsichords etc. and the answer would be yes, indeed there are.

[pianolive]

Like silverwoodpiano says, yes. It is quite common to tune harpsichords using different temperaments.
I have often tuned harpsichords in A415 using a Valotti temp. Actually the harpsichords sound much better in the old temps.
Modern pianos though, are not build for this sound and not build to be tuned lower than 440.