I found a little JavaScript-trick: <script language="JavaScript" type="text/javascript"> if (top.location != self.location) top.location.replace(self.location); </script> Code (markup): that prevent framing of your website pages. For example if user make search on Google Images and get a result as frame. This trick must be placed inside <head></head> tags and works so.. when user clicks on desired image (in Google Images results) it will be redirected to your site so you will not lost traffic. The question.. what do you think if this techique is allowd for Google now?
I doubt Google would mind you doing that as they wouldn't know! But, it might irritate end users, so I wouldn't advise it. If they are purely looking for images, then they won't be interested in the rest of your content anyway.
I've experienced this myself and yes like other above say it's true. Very irritating since you want to click it for enlarge but automatically directs you to the site :|