For me, copy and paste images in the latest version 18.104.22.168 on both 10.6 and 10.7 does not work. It is not just a Lion issue. It doesn't work on either. It quit working on Snow Leopard a while back.
I was able to transfer images using screen capture and the clipboard, and Paste Thought Icon right-clicking on the thought. No luck.
Is there a solution now, or coming in the near future?