A better idea: Palin should offer to submit Trig's birth certificate for examination if Obama would submit his for examination.
Yes, it would be amusing. But it would accomplish nothing.
There's a fine line here. Palin must take command and challenge her critics, but without appearing to play any "victim card".
That's why I suggested a simple statement of fact at the news conference, with no attack on her critics. In fact, I wouldn't mention the controversy at all.
The media will fill in the gaps. But, I'd prefer they didn't. A simple Google search will tell the reader all they need to know. And the best part: it will lead the reader back to the source(s), and a lot of people will be disgusted.
The Obama campaign will be falling all over themselves to disavow any association with this smear. And they will be much more careful in the future to avoid even any appearance of a character smear.