Terry Semel is where the "Yahoo is a media company" thing began.
http://www.zdnet.com/article/can-terry-semel-yahoo/ http://www.wired.com/2007/02/yahoo-3/
I'm still puzzled by Yahoo's hiring Semel, more than any other executive mentioned in this thread. (e.g. hiring Fiorina for HP made sense at the time).
Portals were a big deal. Providing content and being a destination were considered important. They're still important, but apparently being a site that sells classified ads on URL redirects turns out to be a better deal.
I just remember thinking at the time they hired him (and still think): "I use Yahoo for products like Groups, Mail, Messenger, and so on, why are they hiring the guy who greenlit Batman?"
[1] - Another article discussing the topic in the meantime: http://www.businessinsider.com/2008/6/was-yahoo-s-terry-seme...