Is this possible? And if so can you please point me to a tutorial/example perhaps.
Yes it is possible but I don't think any one has done it because the results would be poor.
Do you know how to drive a matrix?
This link shows to what you need to do:-
http://www.thebox.myzen.co.uk/Workshop/LED_Matrix.html
Now let's do some sums.
In a 32 x 32 matrix you have one row on at any one time. You have to refresh this at a rate of at least 30 times a second to avoid flickering.
So that means you must do a row 960 times a second.
Now if you want to superimpose PWM over that you up the rate by the power of the number of PWM bits you want to use. Let's say you want 16 levels of brightness then this is a 4 bit PWM so the refresh rate goes up to 960 X 16 = 15360 times a second. That is about one row in 64uS, this is the same rate as a video signal so it is just about on but there will not be much time to do anything much else.
The other thing is that the on / off ratio is 32 to 1 making the LEDs dim in the first place without dimming them further with the PWM.
[An other alternative is to use the ShiftPWM library
http://www.elcojacobs.com/shiftpwm/](http://An other alternative is to use the ShiftPWM library
http://www.elcojacobs.com/shiftpwm/)
But that many shift registers need buffering correctly.