Actually, you can take up to 5 oz. of fruit juice.

Aside from that, I agree that fruit is not prohibited. I was thinking about taking a watermelon through security, but may instead decide to go low profile to avoid the secondary but totally random bag inspection that would follow...

With that said, the TSA claims that "all liquids ... of any kind are prohibited ... in airport sterile areas." Of course, from concessions to bathrooms to our bodies, this is obviously not the case and unenforceable, so it's just plain wrong to make such a statement. But I'm probably over-thinking things (which is also prohibited by the TSA).