Set/change polygon fillColor on click?

[Knasboll]

Is that possible, and if so, how do i do it?

[Pil]

Try to look at the reference.

http://code.google.com/apis/maps/documentation/javascript/reference.html

Polygon has a method setOptions. So you'd have to use something like
that

poly.setOptions( { fillColor: '#0000ff' });