Welcome to the wonderful world of search engines. They load the page in a frame which gives them legal ability to do that. Since they are serving a snapshot of the image and the full image view actually loads your page, they don't get in trouble.
If it's showing your website (not G1) and you would like to have your page bust out of their frames, here's some code for you:
<!-- Bust out of frames -->
if (window!= top)
<!--End Bust out of Frames -->
Just place this in the header of your HTML document and it will open your page in the current browser in full size, not in a frame.