Ravi Dronamraju noted a couple of months ago (I've only just seen it) a subtle but important point about Yahoo's new Ajaxified homepage:Ex-Yahooligan
"This homepage dropped the concept of website directory completely. I guess the
transformation is complete. Yahoo! is now more about showing people in and around yahoo!
network and not about showing people what’s most useful on the web. Yahoo! is the
new AOL of the web…"
I think the comparison to 90's AOL is a little unfair. Yahoo is using social tools like Y! Answers and MyWeb, along with web services and its developer network, to make external content an important part of its service. Also as one of Ravi's commenters pointed out, search long ago replaced the directory as the primary means of content discovery on the Web.
Nevertheless, it is an interesting point that the new Yahoo homepage links predominantly to Yahoo properties - rather than to external sources, as it did in the old days. The directory service is still there, but has been de-emphasized on the homepage:
The directory was a section on the homepage (albeit near the bottom)...and
...it was also featured as a search option
The directory is still one of the options hanging off the search box - but isn't otherwise featured on the homepage
Perhaps it's just a sign of the times: directories of external websites are out, Yahoo media properties are in.