Even though I kind of mocked Bing's spam tests as being the cause for many people seeing the search share of Microsoft's Bing as seizing market share, it is not the case in most situations. In most situations, the search share you see coming from Bing is legit and search marketers are taking notice.
I track a lot of web sites and in some cases, not all, Bing has overtaken Yahoo as the number two search engine sending traffic to those sites. Google still dominates, but the number two search engine for some sites I track is Bing, not Yahoo anymore.
In a 15 day period, Bing sent this site over 1,000 more visitors then Yahoo did. Of course, this is just one site and who knows, maybe Yahoo doesn't like this site too much. But a lot of webmasters and search marketers are noticing that Bing's share is exceeding Yahoo. Again, not in all cases, but in some. So what does this mean?
If you have not done so already, go to your analytics package and see what search engine is driving you traffic. Note, in Google Analytics, the Bing traffic doesn't really show until June 9th, so maybe adjust your date range to reflect that. Then see the search traffic reports and see where your visitors are coming. Then reallocate your budgets accordingly, based on traffic, conversions and ROI.
Don't get me wrong, I love Yahoo but you have to do what is best for the bottom line.
Forum discussion at WebmasterWorld.