This really is not specific to apple though is it?

It could happen to ANY device be it the iphone, N900 or desktop PC. This sort of mal-ware scam has been around since the late 90s when you could find jpgs with malicious code injected into them. But I suppose the silver lining of this would be to educate users in the dangers of opening unwanted mail.

Let's us all hope that Adobe and other office dev's also hear this and look in to tightening the encryption standards of the PDF format.