Back in 2002, I wrote my Google: Can The Marcia Brady Of Search Stay Sweet? article. I talked about how, similar to Jan's fear that everything was "Marcia, Marcia, Marcia" in the Brady Bunch, search marketers and others were thinking "Google, Google, Google" in the search world.
Well, the other Bradys are getting more attention these days. Google is still the dominant search service, of course, with many webmasters still reporting it's the main source of their search traffic. But Yahoo has its own results, and Microsoft has long had a sizable share as well.
Despite this, are search marketers still focused too much on Google? Our forum thread SEO Thoughts on Google has a good discussion on this, including a long post from me if you care to read more about why I think it's the vertical search areas that marketers really need to plan for.
Another of our forum threads, Confessions of a White Hat Content Spammer: What I've Learned by Ignoring Google, also makes for some thoughtful reading as well on this topic.