Am having an issue converting some MediaWiki pages to PDF with Prince,

Here's an example of the general issue I experience,

http://www.sfu.ca/~jdbates/tmp/css/201004070/

  <img src="http://artefactual.com/images/evelyn.png" style="float: right" />
  <br style="clear: both" />
  <img src="http://artefactual.com/images/richard.png" style="float: right" />

^ in the browsers I tried, the <br syle="clear: both"/> causes the second image to appear after the first

- but in Prince' PDF output the images appear sort of next to each other, http://www.sfu.ca/~jdbates/tmp/css/201004070/index.pdf

Is this a bug in Prince?

Technically no, as in CSS 2.1 the clear property only applies to block elements. However, web browsers may still support it for historical reasons. We may add this back in the future.