When invoking the example in InternetExplorer, the affect of clicking
ellipse is to bring up W3's web page.
I have not found a way of achieving this in inkscape.
What, Inkscape did not show you the web page?! :)
Seriously, it would be nice to run a browser by clicking a link. In
theory. In practice, Inkscape is not so much of a "user agent" as it
is an SVG creating application. In particular, following link on click
will badly get in the way of editing. Clicking something in Inkscape
has lots of editing functions. So, while we can create links, I think
we can be excused for not following them.
This of course applies to inkscape proper. For inkview, following
links by calling a browser is a must. I think we already have an RFE
on that; search in the tracker and add your comments.