The main difference between Mahalo and Yahoo 1.0 - as of 1994 - seems to be the information research inherent in gunning for top search terms instead of "a catalog of the world" - investments in human editing are optimised for traffic. It's like a blog network - with only the links and no content. The tumblelogging of weblogging networks.
Good roundup of differences and similarities with past ideas. A point from that article - you want to be a search site not a destination site - was my immediate reaction when I saw Mahalo - but I also felt that Mahalo had failed to do that. There's too much flavour in the site.

(Bonus unrelated side note from Mahalo founder on virtuous cycles of influence in the evolution of the web.)