As you know a site will gain some PR fractions from the PR of the site where an outbound link to that site is placed. I wonder ... if the outbound links should (randomly) rotate on the site, so they will not be exposed all the time but some of the time... would this affect the PR profit for the sites in the outbound link?
The amount of links that are on the cached-version of the page gets counted. So for your site as a whole rotating the links should not make a bit of difference. You can javascript-code them, so they don't count at all though.