A-ha! So this is how it’s done…
For the full experience you’d need a canvas (or theme) that accommodates the Flickrslideshow minimum dimensions which are roughly 580px wide x 360px high. Right now this site’s main content div is only 500px wide – so there’s a bit of clipping on landscape images. But not enough to worry about too much just yet.
The code is this:
<iframe style="border:0" width="500px" height="400px" src="http://www.flickr.com/photos/lazydada/sets/72157603491230286/show/">