This is a Flickr collage – perhaps a new art form!
First I made the strip of four images, using images posted to Flickr (you can see the strip of four on this page). The strip was made with OberKampf, a Flickr API PHP library of funtions.
To get the strip like it is, I had to copy and flip the Golden Gate Bridge image (Photoshop) so that it could appear twice, once reversed.
Next, with the strip appearing on the page, I used Snag-It to capture the four frames to a .Tif file. The capture was reworked in Photoshop to bring tonality down and to create the transition between the third and fourth frames.
Finally, I reposted the collage to Flickr (and added it to the Tweaked group).