Beneath the last photo is a link in which I posted some multiple exposure photographs that are of different photos. The one on the page I provided is the same photo at different exposure speeds with different colors to which I made the last page.
So if you want to see Multiple Exposure...
I have made a brief tutorial as well as some examples of multiple exposure photography with Picasa3. Go to my website if you would like to know how to do this :)
http://nathanaelvitkus.blogspot.com/2009/08/making-multiple-exposures-with-picasa-3.html