Google vs Yahoo vs MSN vs AskJeeves
The search landscape sure changes fast.
Yahoo's purchase of del.icio.us is yet another indication that they intend to highly leverage the participation of the web community in the rankings process. Google remains very confident in their algorithmic approach, perhaps because they see any forms of user participation as too spammable. Yet Google appears to be under the greatest attack by spammers due to their high market share for search.
Google's brilliant "pagerank" innovation counted on an indirect form of community "voting" through site links, but del.icio.us is a much more robust voting system, especially when Yahoo redesigns the interface to be less geeky.
The search battles are REALLY getting interesting now - MSN Search pretty much let's the computer decide. They have what is perhaps the largest Neural Network in the world and appear to be moving towards a system where humans only intervene in the program to fix serious problems. Google's approach is also algorithmic but appears to involve more "programmer participation" and site filtering than MSN's.
Yahoo, with a history of being the first major web directory along with extensive editorial oversight, has adopted a hybridized algorithm plus editor model, and with today's aquisition of del.icio.us they'll enlist the community in direct voting for sites.
MSN's recent discussion indicates they may soon be paying people to use their search. They also will soon compete with Google Adsense and Yahoo Publisher network to pay for content based ads.
The search landscape, built almost entirely on advertising revenues, is changing at the speed of cash.