It seems as though rich take overs are occurring in two primary locations - in part because the cost of development and implementation is far greater than traditional units: - big destination sites with very large audiences (like Yahoo) - targeted verticals with more measured audiences (ESPN and Wall Street Journal)
Today, Sports Illustrated took over their homepage with a very aggressive, unique unit by Smart Water that featured Tom Brady of the New England Patriots. Not only is unit very targeted (product and personality) but it is specifically crafted for Sports Illustrated (size, the SI.com header is integrated, and so forth). While these ads are highly engaging and attractive - they come at a few costs. First (and mentioned above), they are clearly more difficult to build and implement - but therefore demand high CPMs.
Second, the ad types have diminishing returns over time. For instance, the audience's interest is captured because it is a unique treatment (and therefore not seen as a regular annoyance). If these units appeared on the majority of pageviews, the audience reaction would be much different.