Whenever visting a web page in Safari, I've always been able to resize it by using the two finger 'pinch' gesture. I've always been able to zoom in on small text or reduce large text. Yesterday when following the mars mission at nasa.gov, I came across many pages that can't be resized... Below is a link to one of them. Try open it using your iPad.
Mars Science Laboratory: Participate
I wonder if this is just something unique to my iPad, or if the web page has been designed to somehow defeat the pinch gestures? Am I the only one experiencing this? Is there a fix?