I just did a little testing here, and I see that your formula should work if A3 has a date in it. So I'm guessing what it has is a character string. If so, then you can either translate column A to dates, or change your formula to convert TODAY() to a character string in the format matching column A, like this:
Code:
=$A3=TEXT(TODAY(),"m/d/yy")
That works on my machine.